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I am glad to be able to give wider publicity here to some mature identical with the minute bodies well known to conclusions which I comniunicated to the Jubilee volume microscopists and recognised as crystals modified by a of the “Société de Biologie ” of Paris in 1899. I there disculloid medium. They have been described by Rainey, cussed the significance of the great increase in the size of Harting, and Ord, on different occasions, many years ago. the cerebral hemispheres in recent, as compared with They are not devoid of interest, but cannot be considered as Eocenc Mammals, and in Man as compared with Apes, having any new bearing on the origin of living matter. and came to the conclusion that “the power of building

Psychology.-I have given a special heading to this sub- up appropriate cerebral mechanism in response to individual ject because its emergence as a definite line of experimental experience," or what may be called “ educability,” is the research seems to me one of the most important features in quality which characterises the larger cerebrum, and is the progress of science in the past quarter of a century. that which has led to its selection, survival, and further Thirty-live years ago we were all delighted by Fechner's increase in volume. The bearing of this conception upon psychophysical law, and at Leipzig I, with others of my questions of fundamental importance in what has been day, studied it experimentally in the physiological labora- called genetic psychology is sketched as follows. fory of that gieat ieacher, Carl Ludwig. The physiological " The character which we describe as 'educability' can methods of measurement (which are the physical ones) be transmitted ; it is a congenital character. But the results have been more and more widely, and with guiding intelli- of education can not be transmitted. In each generation gence and ingenuity, applied since those days to the study they have to be acquired afresh. With increased of the activities of the complex crgans of the nervous system • educability' they are more readily acquired and a larger which are concerned with "mind or psychic phenomena. variety of them. On the other hand, the nerve-mechanisms Whilst some enthusiasts have been eagerly collecting ghost of instinct are transmitted, and owe their inferiority as stories and records of human illusion and fancy, the serious compared with the results of education to the very fact experimental investigation of the human mind, and its that they are not acquired by the individual in relation to forerunner the animal mind, has been quietly but steadily his particular needs, but have arisen by selection of conproceeding in truly scientific channels. The science is still genital variation in a long series of preceding generations." in an early phase that of the collection of accurate ob- " To a large extent the two series of brain-mechanisms, servations and measurements-awaiting the development of the instinctive' and the individually acquired,' are in great guiding hypotheses and theories. But much has been opposition to one another. Congenital brain-mechanisms done, and it is a matter of gratification to Oxford men that may prevent the education of the brain and the development through the liberality of the distinguished electrician, Mr. of new mechanisms specially fitted to the special conditions Henry Wilde, F.R.S., a lectureship of Experimental of life. To the educable animal the less there is of Psychology has been founded in the University of Oxford, specialised mechanism transmitted by heredity, the better. where the older studies of Mental and Moral Philosophy, The loss of instinct is what permits and necessitates the Logic and Metaphysics have so strong a hold, and have so education of the receptive brain. well prepared the ground for the new experimental develop- “ We are thus led to the view that it is hardly possible ment. The German investigators W. Wundt, G. E. for a theory to be further from the truth than that expressed Muller, C. Stumpf, Ebbinghaus, and Munsterberg have by George H. Lewes and adopted by George Romanes, been prominent in introducing laboratory methods, and namely, that instincts are due to ‘lapsed ’intelligence. The have determined such matters as the elementary laws of fact is that there is no community between the mechanisms association and memory, and the perceptions of musical of instinct and the mechanisms of intelligence, and that tones and their relations. The work of Goldschneider on the latter are later in the history of the development of the " the muscular sense," of von Frey on the cutaneous sensa- brain than the former, and can only develop in proportion tions, are further examples of what is being done.

as the former become feeble and defective." I The difficult and extremely important line of investiga- Darwinism.-Under the title “ Darwinism” it is contion, first scientifically treated by Braid under the name venient to designate the various work of biologists tending

'Hypnotism." has been greatly developed by the French to establish, develop, or modify Mr. Darwin's great theory sa huol, especially by Charcot. The experimental investiga- of the origin of species. In looking back over twenty-five tion of suggestion," and the pathology of dual conscious- years it seems to me that we must say that the conness and such exceptional conditions of the mind, has been clusions of Darwin as to the origin of species by the greatly advanced by French observers.

survival of selected races in the struggle for existence are The older work of Ferrier and Hitzig on the functions of more firmly established than ever. And this because there the parts of the brain has been carried further by Goltz have been many attempts to gravely tamper with essential and Munk in Germany, and by Schäfer, Horsley, and Sher- parts of the fabric as he left it, and even to substitute conringlon in England.

ceptions for those which he endeavoured to establish, at The most important general advance seems to be the variance with his conclusions. These attempts must, I Tealisation that the mind of the human adult is a social think, be considered as having failed. A great deal of valuproduct ; that it can only be understood in relation with the able work has been done in consequence; for honest special environment in which it develops, and with criticism, based on observation and experiment, leads to which it is in perpetual interaction. Prof. Baldwin, of further investigation, and is the legitimate and natural Princeton, has done important work on this subject. mode of increase of scientific knowledge. Amongst the Closely allied is the study of what is called “ the psychology attempts to seriously modify Darwin's doctrine may be cited of groups," the laws of mental action of the individual as that to assign a great and leading importance to Lamarck's modified by his membership of some form of society.

theory as to the transmission by inheritance of newly French authors have done valuable work here.

acquired characters, due chiefiy to American palæontolThese two developments of psychology, are destined to ogists and to the venerated defender of such views, who provide the indispensable psychological basis for Social has now closed his long life of great work, Mr. Herbert Science, and for the anthropologicai investigation of mental Spencer ; that to attribute leading importance to the action phenomena.

of physiological congruity and incongruity selective breedHereafter, the well-ascertained laws of experimental ing, which was put forward by another able writer and perrhology will undoubtedly furnish the necessary scientific naturalist who has now passed from among us, Dr. George basis of the art of education, and psychology will hold the Romanes; further, the views of de Vries as to discontinuity same relation to that art as physiology does to the art of in the origin of new species, supported by the valuable work medicine and hygiene.

of Mr. Bateson on discontinuous variation ; and lastly, the There can be little doubt, moreover, of the valuable inter- attempt to assign a great and general importance to the facts action of the study of physical psychology and the theories ascertained many years ago by the Abbé Mendel as to the of the origin of structural character by natural selection. cross-breeding of varieties and the frequent production (in The relation of the human mind to the mind of animals, regard to certain characters in certain cases) of pure strains and the gradual development of both, is a subject full of rather than of breeds combining the characters of both rich stores of new material, yielding conclusions of the parents. On the other hand we have the splendid series highest importance, which has not yet been satisfactorily

1 From the Jubilee volume of the Soc. de Biol. of Paris, 1899. Reprinted approached,

in NATURE, vol. Ixi., 1900, pp. 624, 625.

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of observations and writings of August Weismann, who has, has not been extinguished. Change the normal conditions in the opinion of the majority of those who study this of the species in the case of a young individual taken tosubject, rendered the Lamarckian theory of the origin and day from the site where for thousands of generations its transmission of new characters altogether untenable, and ancestors have responded in a perfectly defined way to the has, besides, furnished a most instructive, if not finally

normal and defined conditions of environment; reduce the conclusive, theory or mechanical scheme of the phenomena daily or the seasonal amount of solar radiation to which of Heredity in his book “The Germ-plasm." Prof. Karl

the individual is exposed; or remove the aqueous vapout Pearson and the late Prof. Weldon--the latter so early from the atmosphere; or alter the chemical composition of in life and so recently lost to us—have, with the finest the pabulum accessible; or force the individual to previously courage and enthusiasm in the face of an enormous and unaccustomed muscular effort or to new pressures and difficult task, determined to bring the facts of variation and strains; and (as Lamarck bids us observe), in spite of all heredity into the solid form of statistical statement, and the long-continued response to the carlier normal specific have organised, and largely advanced in, this branch of in- conditions, the innate congenital potentiality shows itself. vestigation, which they have termed " Biometrics." Many The individual under the new quantities of environing naturalists throughout the world have made it the main agencies shows new responsive quantities in those parts of object of their collecting and breeding of insects, birds, and its structure concerned, new or acquired characters. plants, to test Darwin's generalisations and to expand “So far, so good. What Lamarck next asks us to the work of Wallace in the same direction. A delightful accept, as his second law,' seems not only to lack the fact in this survey is that we find Mr. Alfred Russel Wallace support of experimental proof, but to be inconsistent with (who fifty years ago conceived the same theory as that more what has just preceded it. The new character which is fully stated by Darwin) actively working and publishing ex hypothesi, as was the old character (length, breadth, some of the most convincing and valuable works weight of a part) which it has replaced-a response to Darwinism. He is still alive and not merely well, but environment, a particular moulding or manipulation by pursuing his work with vigour and ability. It was chiefly incident forces of the potential congenital quality of the ihrough his researches on insects in South America and the race—is, according to Lamarck, all of a sudden raised to Malay Islands that Mr. Wallace was led to the Darwinian extraordinary powers.

The new or freshly acquired theory; and there is no doubt that the study of insects, character is declared by Lamarck and his adherents to be especially of butterflies, is still one of the most prolific capable of transmission by generation; that is to say, it fields in which new facts can be gathered in support of alters the potential character of the species. It is no Darwin and new views on the subject tested. Prominent longer a merely responsive or reactive character, deteramongst naturalists in this line of research has been and mined quantitatively by quantitative conditions of the is Edward Poulton of Oxford, who has handed on to the environment, but becomes fixed and incorporated in the study of entomology throughout the world the impetus of potential of the race, so as to persist when other quantithe Darwinian theory. I must here also name a writer tative external conditions are substituted for those which who, though unknown in our laboratories and museums, originally determined it. In opposition to Lamarck, one seems to me to have rendered very valuable service in later must urge, in the first place, that this thing has never been years to the testing of Darwin's doctrines and to the bring- shown experimentally to occur; and in the second place. ing of a great class of organic phenomena within the that there is no ground for holding its occurrence to be cognisance of those naturalists who are especially occupied probable, but, on the contrary, strong reason for holding with the problems of Variation and Heredity. I mean Dr. Archdall Reid, who has with keen logic made use of

it to be improbable. Since the old character (length,

breadth, weight) had not become fixed and congenital after the immense accumulation of material which is in the hands of medical men, and has pointed out the urgent

many thousands of successive generations of individuals

had developed it in response to environment, but gave place importance of increased use by Darwinian investigators to a new character when new conditions operated on an of the facts as to the variation and heredity of that unique individual (Lamarck's first law), why should we suppose animal, man, unique in his abundance, his reproductive activity, and his power of assisting his investigator by

that the new character is likely to become fixed after 2 his own record. There are

much shorter time of responsive existence, or to escape more observations about the variation and heredity of man and the conditions attend

the operation of the first law? Clearly there is no reason

(so far as Lamarck's statement goes) for any such supant upon individual instances than with regard to any other animal. Medical men need only to grasp clearly the ques

position, and the two so-called laws of Lamarck are at

variance with one another." tions at present under discussion in order to be able to furnish with ease data absolutely invaluable in quantity

In its most condensed form my argument has been and quality. Dr. Archdall Reid has in two original books

stated thus by Prof. Poulton : Lamarck's " first law full of insight and new suggestions, the “ Present Evolution

assumes that a past history of indefinite duration is powerof Man” and “Principles of Heredity,” shown a new path

less to create a bias by which the present can be confor investigators to follow.

trolled; while the second assumes that the brief history The attempt to resuscitate Lamarck's views on the in

of the present can readily raise a bias to control the heritance of acquired' characters has been met not only by

future" (NATURE, vol. li., 1894. p. 127). the demand for the production of experimental proof that

An important light is thrown on some facts which seem such inheritance takes place, which has never been pro

at first sight to favour the Lamarckian hypothesis by the duced, but on Weismann's part by a demonstration that

consideration that, though an “ acquired character is the reproductive cells of organisins are developed and set

not transmitted to offspring as the consequence of the aside from the rest of the tissues at so early a period that

action of external agencies determining the "acquirement," it is extremely improbable that changes brought about in

yet the tendency to react exhibited by the parent is trans. those other tissues by unaccustomed incident forces can

mitted, and if the tendency is exceptionally great a false be communicated to the germ-cells so as to make their

suggestion of a Lamarckian inheritance can readily result. appearance in the offspring by heredity. Apart from this,

This inheritance of " variation in tendencies to react I have drawn attention to the fact that Lamarck's first and

has a wide application, and has led me to coin the word second laws (as he terms them) of heredity are contra

educability as mentioned in the section of this address dictory the, one of the other, and therefore may be dis

on Psychology. missed. In 1894 I wrote :

The principle of physiological selection advocated by Dr. “Normal conditions of environment have for many

Romanes does not seem to have caused much discussion. thousands of generations moulded the individuals of a

and has been unduly neglected by subsequent writers. 11 given species of organism, and determined as each in

was ingenious, and was based on some interesting observdividual developed and grew 'responsive' quantities in its ations, but has failed to gain support. parts (characters); yet, as Lamarck tells us, and as

The observations of de Vries-showing that in cultivated know, there is in every individual born a potentiality which

varieties of plants a new form will sometimes assert itsell

suddenly and attain a certain period of dominance, though 1 I use the term "acquired" without prejudice in the sense given to not having been gradually brought into existence by a slon that word by Lamarck himself.

process of selection-have been considered by him, and by

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a good many other naturalists, as indicating the way in injured, or diseased organisms is called pathology. It which new species arise in Nature. The suggestion is a necessarily has an immense area of observation and is of valuable one if not very novel, but a great deal of observ- transcending interest to mankind, who do not accept their ation will have to be made before it can be admitted as

diseases unresistingly and die as animals do, so purifying really having a wide bearing upon the origin of species. their race, but incessantly combat and fight disease, proThe same is true of those interesting observations which ducing new and terrible forms of it by their wilful interwere first made by Mendel, and have been resuscitated ference with the earlier rule of Nature. and extended with great labour and ingenuity by recent Our knowledge of disease has been enormously advanced workers, especially in this country by Bateson and his in the last quarter of a century, and in an important degree pupils. If it should prove to be true that varieties when our power of arresting it, by two great lines of study going crossed do not, in the course of eventual inter-breeding, on side by side and originated, not by medical men produce intermediate forms as hybrids, but that characters physiologists in the narrow technical sense, but by are either dominant or recessive, and that breeds result naturalists, a botanist, and a zoologist. Ferdinand Cohn, having pure unmixed characters—we should, in proportion | Professor of Botany in Breslau, by his own researches and as the Mendelian law is shown to apply to all tissues and by personal training in his laboratory, gave to Robert organs and to a majority of organisms, have before us a Koch the start on his distinguished career as a bacterivery important and determining principle in all that relates ologist. It is to Metschnikoff the zoologist and embryto heredity and variation. It remains, however, to be ologist that we owe the doctrine of phagocytosis and the shown how far the Mendelian phenomenon is general. consequent theory of immunity now so widely accepted. And it is, of course, admitted on all sides that, even were We must not forget that in this same period much of the Mendelian phenomenon general and raised to the rank the immortal work of Pasteur on hydrophobia, of Behring of a law of heredity, it would not be subversive of Mr. and Roux on diphtheria, and of Ehrlich and many others Darwin's generalisations, but probably tend to the more to whom the eternal gratitude of mankind is due, has ready application of them to the explanation of many been going on. It is only some fifteen years since Calmette difficult of the structure and distribution of

showed that if cobra poison were introduced into the organisms.

blood of a horse in less quantity than would cause death, Two general principles which Mr. Darwin fully recog- the horse would tolerate with little disturbance after ten nised appear to me to deserve more consideration and more days a full dose, and then day after day an increasing general application to the history of species than he had dose, until the horse without any inconvenience received time to give to them, or than his followers have accorded

an injection of cobra poison large enough to kill thirty to them. The first is the great principle of “ correlation horses of its size. Some of the horse's blood being now of variation, from which it follows that, whilst natural withdrawn was found to contain a very active antidote to selection may be favouring some small and obscure change cobra poison-what is called an antitoxin. The procedure in an unseen group of cells—such as digestive, pigmentary and preparation of the antitoxin is practically the same or nervous cells, and that change a change of selective

as that previously adopted by Behring in the preparation value—there may be, indeed often is, as we know, a corre- of the antitoxin of diphtheria poison. Animals treated lated or accompanying change in a physiologically related with injections of these antitoxins are immune to the part of far greater magnitude and prominence to the eye poison itself when subsequently injected with it, or, if of the human onlooker. This accompanying or correlated

already suffering from the poison (as, for instance, by character has no selective value, is not an adaptation-is, snake-bite), are readily shown by experiment to be rapidly in fact, a necessary but useless by-product. A list of a cured by the injection of the appropriate antitoxin. This few cases of this kind was given by Darwin, but it is is, as all will admit, an intensely interesting bit of biology. most desirable that more should be established. For they

The explanation of the formation of the antitoxin in the enable us to understand how it is that specific characters, blood and its mode of antagonising the poison is not easy. those seen and noted on the surface by systematists, are It seems that the antitoxin is undoubtedly formed from the noe in most cases adaptations of selective value. They corresponding toxin or poison, and that the antagonism also open a wide vista of incipient and useless develop- can be best understood as a chemical reaction by which ments which may suddenly, in their turn, be seized upon the complex molecule of the poison is upset, or effectively by ever-watchful natural selection and raised to a high modified. pitch of growth and function.

The remarkable development of Metschnikoff's doctrine The second, somewhat but by no means altogether of phagocytosis during the past quarter of a century is neglected, principle is that a good deal of the important certainly one of the characteristic features of the activity variation in both plants and animals is not the variation of biological science in that period. At first ridiculed as of a minute part or confined to one organ, but has really “ Metschnikoffism,” it has now won the support of its an inner physiological basis, and may be a variation of a former adversaries. **ole organic system or of a whole tissue expressing itself For a long time the ideal of hygienists has been to preat several points and in several shapes. In fact, we should serve man from all contact with the germs of infection, to perhaps more generally conceive of variation as

destroy them and destroy the animals conveying them, such much the accomplishment and presentation of one little as rats, mosquitoes and other flies. But it has now been mark or difference in weight, length, or colour, as the borne in upon us that, useful as such attempts are, and expression of a tendency to vary in a given tissue or organ great as is the improvement in human conditions which can n 3 particular way. Thus we are prepared for the rapid thus be effected, yet we cannot hope for any really comPrtension and dominance of the variation if once it is plete or satisfactory realisation of the ideal of escape from favoured by selective breeding. It seems to me that such contact with infective germs. The task is beyond human coses as the complete disappearance of scales from the powers. The conviction has now been arrived at that, integument of some osseous fishes, or the possible reten- whilst we must take every precaution to diminish infection, tinn of three or four scales out of some hundreds present yet our ultimate safety must come from within-namely, in nearly allied forms, favour this mode of conceiving of from the activity, the trained, stimulated, and carefully variation. So also does the marked tendency to produce guarded activity, of those wonderful colourless amaba-like mirmbranous expansions of the integument in the bats, corpuscles whose use was so long unrecognised, but has now for only between the digits and from the axilla, but from been made clear by the patiently continued experiments the ears and different regions of the face. Of course, the and arguments of Metschnikoff, who has named them alternative hairy or smooth condition of the integuments 'phagocytes.” The doctrine of the activity and immense both in plants and animals is a familiar instance in which importance of these corpuscles of the living body which a tendency extending over a large area is recognised as form part of the all-pervading connective tissues and foat that which constitutes the variation. In smooth or hairy also in the blood, is in its nature and inception opposed to varietirs we do not postulate an individual development of what are called the “humoral” and “vitalistic” theories of hairs subjerted one by one to selection and survival or resistance to infection. Of this kind were the beliefs that repression.

the liquids of the living body have an inherent and someDiscase.-- The study of the physiology of unhealthy, what vague power of resisting infective germs, and even

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that the mere living quality of the issues was in some polyps, have that sac lined by digestive cells which have unknown way antagonistic to foreign intrusive disease- the same ameboid character as “phagocytes," and actually germs.

digest to a large extent by swallowing or taking into their The first eighteen years of Metschnikoff's career, after individual protoplasm raw particles of food. Such partides his undergraduate course, were devoted to zoological and are enclosed in a temporary cavity, or varvole, into which embryological investigations. He discovered many import- the cell-protoplasm secretes digestive ferment and other ant facts, such as the alternation of generations in the chemical agents. Now there is no doubt that such digestive parasitic worm of the frog's lung—Ascaris nigrovenosa, vacuoles may burst and so pour out into the polyp's stomach and the history of the growth from the egg of sponges and a digestive juice which will act on food particles outside medusæ. In these latter researches he came into contact the substance of the cells, and thus by the substitution of with the wonderfully active cells, or living corpuscles, which this process of outpouring of the secretion for that of inin many low forms of life can be seen by transparency in gestion of food particles into the cells we get the usual the living animal. He saw that these corpuscles (as was form of digestion by juices secreted into a digestive cavity. indeed already known) resemble the well-known amaba, and Now this being certainly the case in regard to the history can take into their soft substance (protoplasm) at all parts of the original phagocytes lining the polyp's gut, it does of their surface any minute particles and digest them, thus not seem at all unlikely, but on the contrary in a higher destroying them. In a transparent water-fiea Metsch- degree probable, that the phagocytes of the blood and nikoff these amaba-like, colourless, floating

tissues should behave in the same way and pour out blood-corpuscles swallowing and digesting the spores

sensitisers and opsonins to paralyse and prepare their bacof a parasitic fungus which had attacked the water- terial food. And the experiments of Metschnikoff's pupils fleas and causing their death. He

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and followers show that this is undoubtedly the case. the conclusion that this is the chief, if not the whole Whether there is any great variety of and difference for value of these corpuscles in higher as well as lower tween “sensitisers ” and “opsonins is a matter which is animals, in all of which they are very abundant. It was still the subject of active experiment. Metschnikoll's conknown that when a wound bringing in foreign matter

clusion, as recently stated in regard to the whole progress is inflicted on a vertebrate animal the blood-vessels become of this subject, is that the phagocytes in our bodies singuld gorged in the neighbourhood and the colourless corpuscles be stimulated in their activity in order successfully to fight escape through the walls of the vessels in crowds. Their the germs of infection. Alcohol, opium, and even quinine, business in so doing, Metschnikoff showed, is to eat up the

hinder the phagocytic action ; they should therefore be foreign matter, and also to eat up and remove the dead, entirely eschewed or used only with great caution where wounded tissue. He therefore called these white or their other and valuable properties are urgently needed. colourless corpuscles “phagocytes,” the eater-cells, and in It appears that the injection of blood-scrum into the tissues his beautiful book on Inflammation, published twenty years

of animals causes an increase in the number and activity of ago, proved the extreme importance of their activity. At the phagocytes, and thus an increase in their resistance the same time he had shown that they eat up intrusive towards pathogenic germs. Thus Durham (who was a bacteria and other germs; and his work for the last twenty

pioneer in his observations on the curious phenomena of years has mainly consisted in demonstrating that they are

the agglutination of blood corpuscles in relation to the chief, and probably the only, agents at work in either disease) was led to suggest the injection of sera during ridding the human body of an attack of disease-causing surgical operations, and experiments recently quoted by germs or in warding off even the commencement of an

Metschnikoff seem to show that the suggestion was well attack, so that the man or animal in which they are fully

founded. After years of opposition bravely met in the pure efficient is “immune "—that is to say, cannot be effectively scientific spirit of renewed experiment and demonstration, attacked by disease-germs.

Metschnikoff is at last able to say that the foundation Disease-germs, bacteria, or protozoa produce pois stone of the hygiene of the tissues—the thesis that our which sometimes are too much for the phagocytes, poison- | phagocytes are our arms of defence against infective germs ing them and so getting the upper hand. But,

-has been generally accepted. Metschnikoff showed, the training of the phagocytės by

Another feature of the progress of our knowledge of weak doses of the poison of the disease-germ, or by weak

disease-as a scientific problem-is the recent recognition ened cultures of the disease-germ itself, brings about a that minute animal parasites of that low degree of unicellupower of resistance in the phagocytes to the germ's poison,

lar structure to which the name “ Protozoa" is given, are and thus makes them capable of attacking the germs

the causes of serious and ravaging diseases, and that the and keeping them at bay. Hence the value of inocula- minute algoid plants, the bacteria, are not alone in posses. tions.

sion of this field of activity. It was Laveran-a French The discussion and experiments arising from Metsch

medical man--who, just about twenty-five years ago, disnikoff's demonstrations have led to the discovery of the covered the minute animal organism in the red blood-oorproduction by the phagocytes of certain exudations from puscles, which is the cause of malaria. Year by year ever their substance which have a most important effect in since our knowledge of this terrible little parasite has weakening the resistance of the intrusive bacteria and increased. We now know many similar to, but not identical rendering them easy prey for the phagocyte. These are with it, living in the blood of birds, reptiles, and frogs. called “sensitisers,” and have been largely studied. They It is the great merit of Major Ross, formerly of the Indian may be introduced artificially into the blood and tissues so Army Medical Stafi, to have discovered, by most patient as to facilitate the work of the phagocytes, and no doubt it and persevering experiment, that the malaria parasite passes is a valuable remedial measure to make use of such sensi- a part of its life in the spot-winged gnat or mosquito tisers as a treatment. Sir A. E. Wright considers that such (Anopheles), not, as he had at first supposed, in the sensitisers are formed in the blood and tissues independ- common gnat or mosquito (Culex), and that if we can get ently of the phagocytes, and has called themopsonins,” rid of spot-winged mosquitoes or avoid their attentions, or under which name he has made most valuable application even only prevent them from sucking the blood of malarial of the method of injecting them into the body so patients, we can lessen, or even abolish, malaria. facilitate the work of the phagocytes in devouring the This great discovery was followed by another as to the hostile bacteria of various diseases. Each kind of disease- production of the deadly " Nagana " horse and cattle disease producing microbe has its own sensitiser or opsonin ; hence in South Africa hy a screw-like, minute animal parasite, the there has been much careful research and experiment re- Trypanosoma Brucei. The Tsetze fly, which was already quired in order to bring the discovery to practical use. known in some way to produce this disease, was found by Metschnikoff himself holds and quotes experiments to show Colonel David Bruce to do so by conveying by its bite the that the “opsonins” are actually produced by the pha- Trypanosoma from wild big-game animals, to the domestigocytes themselves. That this should be so is in accord- cated horses and cattle of the colonists. The discovery of ance with some striking zoological facts, as I pointed out the parasite and its relation to the fly and the disease was nearly twenty years ago. For the lowest multicellular as beautiful a piece of scientific investigation as biologists animals provided with a digestive sac or gut, such as the have ever seen, A curious and very important fact was

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as to

discovered by Bruce-namely, that the native big game this, far more money is required than is at present spent (zebras, antelopes, and probably buffaloes), are tolerant of in that direction. It is necessary, if we are to do our the parasite. The Trypanosoma grows and multiplies in utmost, to spend a thousand pounds of public money on their blood, but does not kill them or even injure them. this task where we now spend one pound. It would be It is only the unaccustomed introduced animals from reasonable and wise to expend ten million pounds a year Europe which are poisoned by the chemical excreta of the of our revenues on the investigation and attempt to destroy Trypanosomes and die in consequence. Hence the wild disease. Actually, what is so spent is a mere nothing, a creatures-brought into a condition of tolerance by natural few thousands a year. Meanwhile our people are dying selection and the dying out of those susceptible to the by thousands of preventable disease. poison-form a sort of " reservoir " of deadly Trypanosomes

II. The ADVANCEMENT OF SCIENCE AS MEASURED BY for the Tsetze flies to carry into the blood of new-comers.

SUPPORT GIVEN TO IT BY Public FUNDS, AND THE RESPECT The same phenomenon of “reservoir-hosts" (as I have else

ACCORDED TO SCIENTIFIC WORK BY THE BRITISH Governwhere called them) has since been observed in the case of

MENT AND THE COMMUNITY AT LARGE. malaria ; the children of the native blacks in Africa and in other malarious regions are tolerant of the malarial parasite, Whilst I have been able, though in a very fragmentary as many as 80 per cent. of children under ten being found and incomplete way, to indicate the satisfactory and, to be infected, and yet not suffering from the poison. This indeed, the wonderful progress of science since this is not the same thing as the immunity which consists in Association last met in York, so far as the making of repulsion or destruction of the parasite.

new knowledge is concerned, I am sorry to say that there The Trypanosomes have acquired a terrible notoriety is by no means a corresponding advancement of Science within the last four years, since another species, also carried in that signification of the word which implies the increase by a Tsetze fly of another species, has been discovered by of the influence of science in the life of the community, Castellani in cases of sleeping sickness in Uganda, and the increase of the support given to it, and of the desire demonstrated by Colonel Bruce to be the cause of that to aid in its progress, to discover and then to encourage awful disease. More than 200,000 natives of Uganda have and reward those who are specially fitted to increase died from it within the last five years. It is incurable, and, scientific knowledge, and to bring it to bear so sad to relate, not only a certain number of European promote the welfare of the community. I am speaking employés have succumbed to it in tropical Africa, but a on a privileged occasion to a body of men who are met brave young officer of the Army Medical Corps, Lieutenant together for the Advancement of Science, and I claim the Tulloch, has died from the disease acquired by him in the right to say to them, without offence to the representatives course of an investigation of this disease and its possible of institutions which I criticise, what is in my mind. cure, which he was carrying out, in association with other It is, unfortunately, true that the successive political men of science, on the Victoria Nyanza Lake in Central administrators of the affairs of this country, as well as Africa. Lieutenant Tulloch was sent out to this investiga- the permanent officials, are altogether unaware to-day, as tion by the Royal Society of London, and I will venture to they were twenty-five years ago, of the vital importance of ask you to join that body in sympathy for his friends, and that knowledge which we call science, and of the urgent admiration for him and the other courageous men who risk need for making use of it in a variety of public affairs. their lives in the endeavour to arrest disease.

Whole departments of Government in which scientific Trypanosomes are now being recognised in the most knowledge is the one thing needful are carried on by diverse regions of the world as the cause of disease-new ministers, permanent secretaries, assistant secretaries, and horse diseases in South America, in North Africa, in the clerks who are wholly ignorant of science, and naturally Philippines and East India are all traced to peculiar species enough dislike it since it cannot be used by them, and is of Trypanosome. Other allied forms are responsible for

in many

instances the condemnation of their official Delhi-sore, and certain peculiar Indian fevers of man. A

employment.
Such officials are, of course,

not to be peculiar and ultra-minute parasite of the blood cells causes blamed, but rather the general indifference of the public Texas fever, and various African fevers deadly to cattle. In the unreasonable way in which its interests all these cases, as also in that of plague, the knowledge of neglected. the carrier of the disease, often a mite or acarus—in that A difficult feature in treating of this subject is that when of plague the flea of the rat-is extremely important, as one mentions the fact that ministers of State and the well as the knowledge of reservoir-hosts when such exist. officials of the public service are not acquainted with

The zoologist thus comes into closer touch than ever science, and do not even profess to understand its results with the profession of medicine, and the time has arrived or their importance, one's statement of this very obvious when the professional students of disease fully admit that and notorious fact is apt to be regarded as a personal they must bring to their great and hopeful task of abolish- offence. It is difficult to see wherein the offence lies, for ing the diseases of man the fullest aid from every branch no one seeks to blame these officials for a condition of of biological science. I need not say how great is the things which is traditional and frankly admitted. contentment of those who have long worked at apparently This is really a very serious matter for the British useless branches of science, in the belief that all know- Association for the Advancement of Science to consider ledige is good, to find that the science they have cultivated and deal with. We represent a line of activity, a group has become suddenly and urgently of the highest practical of professions which are in our opinion of vital importvalue.

ance to the well-being of the nation. We know that those I have not tiine to do more than mention here the effort interests which we value so highly are not merely ignored that is being made by combined international research and and neglected, but are actually treated as of no account cooperation to push further our knowledge of phthisis or as non-existent by the old-established class of politicians and of cancer, with a view to their destruction. It is

and administrators. It is not too much to say that there only since our last meeting at York that the parasite of is a natural fear and dislike of scientific knowledge on Phthisis or Tubercle has been made known; we may hope the part of a large proportion of the persons who are that it will not be long before we have similar knowledge devoid of it, and who would cease to hold, or never have as to Cancer. Only eighteen months have elapsed since held, the positions of authority or emolument which they Fritz Schaudinn discovered the long-sought parasitic germ now occupy, were scientific knowledge of the matters with of Syphilis, the Spirochaeta pallida. As I write these which they undertake to deal required of them. This is a wards the sad news of Schaudinn's death at the age of thorny subject, and one in which, however much one may thirty-five comes to me from his family at Hamburg-an endeavour to speak in general terms, it is difficult to irreparable loss.

avoid causing personal annoyance. Yet it seems to me Let me finally state, in relation to this study of disease, one which, believing as I do that it is of most urgent what is the simple fact-namely, that if the people of importance, it is my duty as your President to press upon Britain wish to make an end of infective and other diseases the attention of the members of the British Association. they must take every possible means to discover capable Probably an inquiry into and discussion of the neglect investigators, and employ them for this purpose. To do of science and the questionable treatment of scientific men

to

are

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