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Heating on a borax bead in the outer and inner flames. Heating on a carbonate of soda bead. Heating on charcoal (if a white mass resulted, which with cobalt

nitrate gave a “ faint pink," the metal might be recogVALITATIVE CHEMICAL ANALYSIS.

nised here, but as magnesium sulphate does not readily 'ative Analysis Tables and the Reactions of certain yield this reaction in most cases the student would pass anic Substances. By E. A. Letts, D.Sc., Ph.D.,

on). Heating on charcoal with sodium carbonate. S.E., F.C.S., &c. (Belfast: Mayne and Boyd, Heating in a glass tube closed at one end. Repeat

ing with bisulphate of potash. Repeating with black author in his preface says, “ Every teacher has Aux. Repeating with magnesium wire. He would then ris own methods-acquired not only from his ex dissolve the substance in water, and test a part of the e, but also largely through the researches of others solution for ammonia by heating it with caustic alkali. this book embodies mine.” Therefore the volume Then heat a part on a platinum wire for the flame fail to be welcome to those who take an interest colouration, a test that has already been done on the teaching of analytical chemistry. But it is sur- ! solid, and then pass on to the examination of the soluto find that Prof. Letts has until quite recently tion in the ordinary way for the base, and finally search d the old method of dictating reactions and for the acid if it is not already found. It may be taken Is to his students, and allowing them to work from for granted that this fiddling about with the substance is wn notes. For the last fifteen years there has not intended, but the volume does not appear to contain ) lack of text-books of qualitative analysis, and directions as to how to go more directly to work. etts has found, what probably all teachers of the The want of system that we complain of is acknoware aware of, that students rarely take accurate ledged by the author himself in picking out certain parts But, however exact they may be, every one knows and labelling them as “systematic." If the whole were nuscript is not so easily deciphered nor so readily systematic this distinction would obviously be meaningIto as a printed page.

less. As this fault exists in many of the text-books and methods of work given are, of course, more or in much of the teaching that we have had experience of, he ordinary lines. The final test for bismuth de- we are tempted to make a few general remarks upon the pon the production of its black suboxide, and this matter without special reference to the volume under has much to recommend it, though probably many | notice. refer the oxychloride reaction. The use of am- That qualitative analysis is often regarded as a 1 molybdate as a separative reagent in qualitative very unimportant branch of chemistry, may account we do not consider advisable for many reasons, for its comparative neglect. One constantly meets with omplaint can be lodged against it on the score of students who are able to perform quantitative operations "acy.

of not too complex a character with commendable can be no doubt whatever that both Prof. Letts accuracy, and that can with a little guidance do many students will find considerable advantage in the sorts of “research work,” but are wholly unable to peroldly-printed statements of methods. But the form with certainty a qualitative analysis of a comparavegins his preface by stating that although the tively simple substance. They may happen to find most is been written chiefly for his own students, he or all of its constituents, but they have no confidence in glad if it prove of service to others also. This their result ; they do not feel sure that they have missed volume open to general criticism, and prompts nothing, or indeed that everything they have found is aplain that it is neither so clear nor so systematic unmistakably present, and generally they have little if ht have been. As to the want of clearness, there any idea of the degree of accuracy of their work. They

expressions that can easily be altered in a second cannot distinguish between a principal constituent and ind these we lay no particular stress upon. For one that is present in a comparatively small proportion.

at page 27, in the description of Bunsen's dry | This incompetency must be ascribed very largely to the read :-“ The charred end of the match is next fact that students are too often urged on to work that a d with fused carbonate of soda.” At page 40 it casual observer might regard as more important. The ut the solution “is mixed with its own volume of foundation is neglected for the sake of the superstructure. of ammonium.” One assumes this to be a solu- But having regard only to that amount of practice in if so the strength of it is not given, and we fear qualitative work that still remains possible for the pulk of the solution to which it is to be added average student, there is too often a lack of method that tely to vary enormously according to the pecu- | is surprising if not disastrous. As a rule, it is conf the student and the character of the substance sidered desirable to get first an idea of the general 'ork upon.

character of the substance given for examination yre important want of clearness may be exempli- | by a few dry tests, but these, as often done, are not only king the case of a student who has Epsom salts of no use, but serve in a conspicuous manner to train the im as a simple salt. This can hardly be called student in the making of careless and imperfect observa-the-way substance, but so far as we can tions, and in the dodging about from one operation to

the student in following these tables would | another with no idea of the proper sequence or inter-depent by the following series of operations : Heat dence of the various parts of the work. In the analytical latinum wire to see the colour of the flame. examination of even the simplest of substances, from the

time when the student receives it until he has made his tains a short history of the arguments and exper last note, every operation ought to be in an order for which led to the substitution of the ether theory which very definite reasons can be given, and the com- trical action in the place of the older action-at-1-1 pleted work ought to be of such a character that any- | theories. While admitting the existence of a a thing added to it would be superfluous ; anything taken which transmits both optical and electrical distan from it would leave it imperfect ; and any change in the the author thinks it more probable that gravitas order of its various parts would be to its detriment. This true action-at-a-distance, and in so doing he tacizo character of work is generally sought after in the separa that a medium is a necessity. The notion of an emper tion of metals from a solution ; but the rest of a qualita- is so foreign to English men of science of this gesa tive analysis, namely the preliminary examination and the that we certainly consider Prof. Sohncke's sung testing for acids, is too often a collection of odd opera- of the question to be worthy of attention. Hes tions, which, if the student is lucky, will lead him sooner or “ Even if we could finally succeed in provingib later to the desired result, but if he is unlucky may fail to at-a-distance is really the result of a transmission: do so through no fault of his own.

some medium, we must not suppose that all è CHAPMAN JONES. are then removed. For the process of such at !

sion is by no means simple, and cannot be ex without further assumptions ; on the contrary,

midable difficulties arise even here. Directly w POPULAR LECTURES ON PHYSICAL give a concise explanation of the compression of SUBJECTS.

and its subsequent expansion when performing Gemeinverständliche Vorträge aus dem

vibrations, we find that a choice must be made 1

Gebeite der Physic. Von Prof. Dr. Leonhard Sohncke. (Jena :

two assumptions equally hard to accept. Either

is itself capable of compression and expansion, 3 Gustav Fischer.)

consists of separate vibrating atoms to whicho IT is a matter of common remark that the books on assign the property of exerting mutual forces: 1 scientific subjects which reach us from Germany are, other at a distance.” as a rule, so special and detailed in character as to be From a purely scientific standpoint, the de totally devoid of interest, except to those immediately “Newer theories of atmospheric electricity and: concerned with the subjects of which they treat. This storms ” is undoubtedly the most valuable of the being the case, it is all the more refreshing to meet with the subject being one on which Prof. Sohncke a such a collection of popular addresses as Prof. Sohncke with some authority. After describing the older has gathered together in the volume before us. He has of the origin of electrical charges in the atmosp not restricted himself in his choice of subjects to any one discusses those newer ones which were suggests branch of physics ; on the contrary, the nine lec- discovery of Hertz that ultra-violet light faci tures of which the book is made up represent as discharge of electricity from a charged body.i many different divisions of natural philosophy, and were the best known is that of Arrhenius, who suppese delivered quite independently before various audiences ordinarily a dielectric, to be rendered feeblyor in Germany.

by the action of light. According to this theory, The first lecture of the series bears the somewhat is negatively charged, and when its atmosphere ! obscure title, “ What then?” and was suggested by a nated some of the charge is conducted away to great strike among the coal-miners of Westphalia, which | The conduction must be electrolytic, otherwis led to a temporary cessation of the German coal supply. would become charged. Prof. Sohncke object The author depicts what would be the consequences if theory mainly on the ground that the discharga the world's coal supply were exhausted, in terms almost of light cannot be considered as due to the 21 as pathetic as those of Prof. Jevons which moved an Eng way, since it is manifested only when the light lish Parliament to appoint a commission on the subject. fall on, and are absorbed by, the negative e But recognizing that, after all, coal is only stored up solar Further, it is not easy to see how elementary 3 energy, Prof. Sohncke endeavours to look at the brighter as oxygen and nitrogen can be electrolyte side of the question by discussing the possibility of utilis- cluding he defends his own theory, accordag ing the sun's energy in other forms, and so enabling man atmospheric electricity is produced when a to remain “lord of creation" even in those days when the with particles of ice meets another charged entire available coal supply of the world reposes on the drops, the electrification being due to the tri shelves of some scientific museum.

against water. In support of his view the achie Equally spontaneous is the lecture on “Migratory the fact that hailstones are found to be elecom Mountains," in which an account of a holiday visit to the reaching the ground. north-east corner of Germany gives an opportunity of de | The appearance of a volume like the preser. I scribing the formation and movements of the mammoth variably gives rise to some regrets that the sand-dunes in that locality.

is no longer of one language and one speech, Of the other lectures, that entitled " The revolution in that some friend of popular science may be our views concerning the nature of electrical actions” | the contents of the book to furnish a tres will probably commend itself to most readers because it English readers. treats of a subject now exciting general interest. It con



references, the synonyms, and the cross-references; in

the smaller the geological horizon and the more importulogue of British Jurassic Gasteropoda, comprising

ant localities, the locality first named being that from jenera and Species hitherto described, with refer

which the type was obtained or the first place from which to their Geological Distribution and to the Local- | the species was recorded in Britain. The dates of pubin which they have been found. By W. H.

lications are often omitted, but since they can be found leston, M.A., F.R.S., P.G.S., and Edward Wilson, l in the bibliography this is not very inconvenient except S. 8vo, pp. xxxiv +147. (London: Dulau and

in the case of serials. The present locale of types is not 1892.)

given, although this would have been a comparatively KT in importance to a monograph on any group | easy matter, especially since so many catalogues of types of fossils is a catalogue of the species giving their have been recently published. ition, their synonymy, and references to the figures | With regard to the orthography the authors have kept 'scriptions. The value of such a catalogue is į to the older and more usual method. For instance, the vusly increased when, as in the present case, the capital initial is used for species when derived from i have made a prolonged and careful study of the proper names, and the single i for the genitive is not . The late Prof. John Morris was able, with always adopted. Thus we find a considerable variation y any help from other workers, to publish a critical in the terminations, such as, Cricki (p. 124) Crickii ue of all British fossils ; the first edition appeared (p. 77), Waltoni (p. 42) Waltonii (p. 139), Suessea (p. 29) in the second in 1854. But since that date so much Suessiï (p. 138), Wrightii (p. 46) Wrightianus (p. 70). is has been made in palæontology that the accom These are, however, purely matters of opinion and do not ent of such a task by any one man would now be in any way detract from the great value of the work, possibility. Prof. Morris always hoped to bring which exhibits so much painstaking accuracy and sound third edition of his work, and after his death


H. WOODS. nittee was formed to carry out this project. But our appears to have been too great and the comsoon ceased to exist. This is greatly to be re

OUR BOOK SHELF. , for although the work must of necessity have The Year-Book of the Imperial Institute of the United istributed among various authors, a certain amount Kingdom, the Colonies, and India, and Statistical ormity in treatment would at any rate have been

Record of the Resources and Trade of the Colonial 1 and publication hastened.

and Indian Possessions of the British Empire. Com

piled chiefly from official sources. First issue 1892. le preface we are told that Mr. Hudleston is mainly

Issued under the authority of the Executive Council, sible for the Oolites and Mr. Wilson for the Lias. and published by John Murray, &c. Large octavo the term Jurassic the authors include everything pp. xvi. and 824. le Lias to the Portland-stone : the Rhætic beds, THE Imperial Institute has lost no time in issuing a h not regarded as strictly Jurassic, are treated in handsome and comprehensive year-book, compiled by plement. The total number of gasteropods re- | the Librarian, Mr. J. R. FitzGerald, who has diligently by Samuel Woodward from these formations in

and successfully gathered together a stack of varied

information bearing on the purposes of the Institute. It vas only 89, whereas in the present work the

is a question which time alone can answer whether rgiven is 1015. Of these 15 come from the Rhætic,

amongst the many admirable year-books of statistics, m the Lias, 681 from the Oolites, and 5 from the commerce, and the colonies which have established id Oolites. In the Lias the gasteropods are char themselves as annuals of proved utility, there is room for ed by the species belonging to comparatively few

a new and bigger book overlapping their information, Although, as far as genera are concerned, the

and containing few, if any, novel features. It would be

out of place to discuss this question in a notice which ows considerable affinity to the Colites, there is

ought to be confined to the scientific aspects of the work. leless a great break in the continuity of the species, The object of the year book, as expressed in the preface, e being common to the Lias and Oolites. Gastero- | is to deal “statistically with the physical geography, the

e most abundant in the calcareous beds, so that | natural resources, and the industries and commerce of wer Oolites have yielded by far the larger number

the Colonies and India," and with certain other related

facts. It would not be fair to criticise severely the first as, the Inferior Oolite being richer than the Great

issue of so large and comprehensive a compilation ; but In the Middle and Upper Oolites there is a de- it would help towards the attainment of the compiler's lecline in the gasteropods, especially of the argill aim if the description of the physical geography of the beds.

regions touched upon could be made as full as the histhe introductory remarks the authors give a torical introductions, and as statistical as the commercial e bibliography of the British Jurassic Gasterpoda,

tables. More notice ought to be taken of the geology

and the character of the soil in the colonies where n a list of the genera, in which each is placed in

geological surveys are in progress; and climate certainly ier family and reference given to the original de deserves better treatment. We do not think space would n. By the use of different type the genera are be wasted in giving the mean monthly temperatures and

into four classes, (1) those fully accepted by the rainfall for the average year, and for two extreme years, , (2) those accepted with doubt, (3) those given as | at a few representative stations in the larger colonies. by other authors but not accepted, (4) synonyms.

This information cannot indeed be found in any existing

books, but must be worked out from original records catalogue proper the authors have adopted

which exist abundantly, and are rarely made available to s plan, each page being divided into two columns ; , practical workers. larger are given the name of the species, the ! The treatment of natural resources might also be

improved by a firmer grasp of scientific principles. The meter and his own, gives 22.62 as the actual reading of commercial statistics are, as might be expected, much

stics are as might be expected. much zero. I have not at the present moment access to Ror fuller, better arranged, and more serviceable than those

paper, and have no note of the date at which this con relating to physical geography; but we imagine that few

was made (either 1879 or 1880).

Such a formula as that given by Mr. Young can, but members of the Imperial Institute, likely to make

only have a limited application. The zero of a theme use of the book, are without the original records relating

depends on the temperature at which the thermometer har to their own department. The difficulty of propor

kept previous to its immersion into ice, and with people tion and perspective is rather seriously apparent

annealed thermometers the secular changes are much a in the treatment of India, which has to be passed over than the temporary ones. Last winter Joule's thermometers more lightly than the colonies, because equal detail changes in zero from 23:51 to 23:00 on the arbitrary some would involve the sacrifice of much space. Thus the great original temperatures varying from 7° to 30. internal trade of India is scarcely touched upon, and the All observations lead to the conclusion that the wants and tastes of consumers in the ultimate Indian changes of a thermometer gradually vanish, so the the market, by whom imports are finally absorbed, are not

corresponding to any temperature approaches a lisit. laid before the British merchant.

Young's formula would make the zero rise indefinitelt.

ARTHUR SCRO Beneath Helvellyn's Shade. By Samuel Barber. (London: Elliot Stock, 1892.)

Dust Photographs and Breath Figures This book consists of notes and sketches in the Valley | YOUR two correspondents on February 9 add interstit of Wythburn, and is brightly and attractively written.

stances of these phenomena. I am sorry that one of my size] Perhaps the best chapters are those on clouds, the

was not clear. In saying "Two cases have been reports various forms of which have been carefully studied by

where blinds with embossed letters have left a later in the author. He has also many interesting remarks on

the window near which they lay," I meant to describe various aspects of Cumberland scenery, on the customs

not in contact.

* I have questioned my neighbour Dr. Earle again 8:5 of the people, and on antiquities. Occasionally, perhaps,

case. The plate-glass window of an hotel in London has a Mr. Barber adopts too much the tone of a preacher, but inside a screen of ground glass lying near bat bot er his impressions and ideas are for the most part upon the latter are the words “Coffee Room" in der fresh and vivid. The book will especially please frosted letters. One day as he was at breakfast the screen those who have themselves felt the charm of Words taken away, but the words were left plainly visible or worth's country.

window, and no washing would remove them. The other curiously similar, but each narrator was ignorant of the tale. A friend, Mr. Potter, asked me if I knew wbehera

in which he was lodging had been an hotel, for on ning LETTERS TO THE EDITOR.

they saw “ Coffee Room" on one of the windows. Iresci [The Editor does not hold himself responsible for opinions ex

the house had been an hotel two or three years premios pressed by his correspondents. Neither can he undertake

there had been brown gauze blinds with gilt letters. to return, or to correspond with the writers of, rejected

Mr. Thiselton-Dyer's observation appears not so me manuscripts intended for this or any other part of NATURE.

these two as to the dust picture of a water-colour des No notice is taken of anonymous communications. ]

which I spoke in my former paper.

I look forward to seeing the effects at Canterbury. Dr. Joule's Thermometers.

Winchester College, February 13.

W. B. RESPECTING the question asked by Mr. Young (Nature, vol. xlvii. p. 317), I am glad to have an opportunity of stating

Fossil Plants as Tests of Climate. that shortly after Joule's death I obtained the sanction of his MR. DE RANCE's note relating to the above sto son to examine the scientific apparatus that were left in his NATURE, P. 294, mentions that “Heer has determin house.

nificent flora of more than 350 species from these I found a number of thermometers, and amongst them the tertiaries, and that he at once pointed out the absences two chiefly used by Joule in his researches. These thermo. | and subtropical forms." My contention, founded on a meters have been placed in my charge for the present. I have study of his determinations and of the original specs made careful comparisons of them with a standard of the London and Dublin, and to some extent in Copenhagen “ Bureau international des Poids et Mesures," and therefore not fifty, or perhaps not the half of fifty, of these dete indirectly with the air or hydrogen thermometer. A standard are entitled to the smallest weight ; and again that thout issued by the Technische Reichsanstalt has also been used as a he saw nothing subtropical in the flora, he subsequently check. I spent a good part of last winter on the work and am the presence of palms, &c., upon utterly insuficient in now only waiting for an opportunity to repeat some of the | however, wishing to rid the " magnificent ” flora of 300 31 measurements. The results will be published in due course, useless and misleading encumbrances, I am far fror and I think will prove of interest. “As Joule compared his depreciate the extraordinary significance and value oft thermometers with one used by Rowland, we shall in this way remains, and which clearly shows that in early Eoce have an indirect comparison of Rowland's air thermometer with coast of Greenland supported in certain places forests those by which the Berlin and Paris standards have been in included the redwood, the plane, and even the magas dependently fixed.

ciated with many more northern forns. This is consis One question arises on which I should be glad to have some the tropical vegetation existing during a part of the pre information, and I should be grateful to any of your readers temporary lower tertiary period in the south of Englant who could help me. The glass of which Joule's thermometer facts are sufficiently inexplicable, but there is no es is made does not behave like the English glass now in use ; | magnify the difficulties they present. As to the Greenland and it would be important to know the probable composition they have not been proved to contain any forest trees to of glass used in England about the year 1840 for thermometric not, and which in fact do not, flourish in their modas purposes. As my experiments are not concluded I do not wish sentatives, when planted in certain favourable spots | to speak with too great a certainty; but I believe it will be found coast of Ireland, and even of Scotland. We are sot eren that if we could return to the glass of Joule's thermometer, we to assume that Greenland as a country was characteris should have a substance as well and possibly even better adapted vegetation, for this might be as erroneous as to regards to the manufacture of thermometers than the modern Jena or Scotland as countries generally characterised by French thermometer glass.

arbutus. The flora of a country is in fact most like you I am sorry I cannot give a very definite answer to Mr. Young's served in its most sheltered spois, in lake bottoms question. Joule does not, as far as I know, anywhere give the | Killarney, or where small rivers quietly steal into the actual readings of the freezing point, but only its changes. of deeply recessed bays like those of Bantry and Es Rowland, in quoting the comparison between Joule's thermo- forest pools like some in the Mount Stewarts woodsst

backwaters and marginal pools of the lower reaches of Unusual Origin of Arteries in the Rabbit. rivers ; we are not only entitled, but we are bound to

Towards the close of last month Prof. W. N. Parker reler this to have been the case in Greenland, and to base timate of its climate in the lower tertiaries upon this view

ported in your columns an abnormality in the veins of the rabbit, o other. Now what geologists and physicists ought to do,

and although the same interest does not attach to it, it may be hat they resolutely won't do, is before going farther afield

| worth while recording an unusual arrangement of the vessels ise and effect, to take the map of the world on Mercator's

arising from the aortic arch. In the case which has just come Lion, and consider how far, if the Atlantic were a closed

under my notice, the two carotids arise together from the arch, to the north, as we know it must have been, the required

at the point usually occupied by the innominate artery, while the ic conditions would be produced. The difference between

right subclavian artery arises beside the left subclavian, which

occupies the usual position. lutus nooks of Ireland on the one side and the desolation of

Philip J. White. dor on the other is brought about solely by ocean currents.

University College of North Wales, February 7. period of the Greenland floras the arctic currents were ed, and consequently the whole Atlantic basin was filled le circulation of equatorial and temperate waters only.

Holmes's Comet. istribution of plants and animals renders it extremely le that during much of the tertiary period, the antarctic

On February 11, ioh. to roh. 35m., I re-observed this object were equally excluded from the Atlantic by land con

with powers of 40 and 60 on my newly-silvered 10-inch reflector. Africa and South America. What, under these circum- !

The comet was in the same field as B Trianguli and south pre, would happen to the climate of the Atlantic littoral ? | ceding that star. I found it fairly conspicuous. The nucleus, d, it appears to me. be more philosophical to dispose of | or brighter portion of the head, presented a distinctly granulated estion, which is supported by a weight of evidence, before appearance. Applying a power of 145, single lens, I saw that ig shisting of the earth's axis, or other hypothetical causes

it really consisted of a number of very small knots of nebu. ed by none. J. STARKIE GARDNER.

losity, so closely approximating the stellar form that they might lon, February 13.

readily have been mistaken for one of the very faint, barely

resolvable clusters in which the components are only to be caught An Optical Phenomenon.

by glimpses. The multiple nucleus was involved and surrounded Ature, vol. xlvii. p. 303, you mention that “a beautiful

with feeble nebulosity, and a faint tapering tail flowed from it in

a N.E. direction. I believe that outlying this there was an exphenomenon, which has not yet been satisfactorily ex; is described by M. F. Folie in the Bulletin of the

cessively faint fan-shaped tail, but could not be absolutely Academy.” From what follows, it is evidently the

certain. ; that described in Tyndall's “Glaciers of the Alps”

The sky was not good, being lighter than usual, with suffused y, 1860), p. 177 et seq. Tyndall gives a description of

mist. On February 12, at roh. 15m., I picked up the comet etter from Prof. Necker to Sir David Brewster, from

again, but details were invisible, owing to the veil of thin cloud I quote the following :-“ You must conceive the

overspreading the N.W. sky at the time. r placed at the foot of a hill between him and the place

Bristol, February 13.

W. F. DENNING. he sun is rising, and thus entirely in the shade; the nargin of the mountain is covered with woods, or detrees and shrubs, which are projected as dark objects on bright and clear sky, except at the very place where the HELMHOLTZ ON HERING'S THEORY OF ust going to rise ; for there all the trees and shrubs bor

COLOUR. the margin are of a pure and brilliant white, appearing :ly bright and luminous, although projected on a most THE following translation of the critical account given t and luminous sky. You would fancy you saw these 1 by von Helmholtz of the colour-theory of E. Hering, ade of the purest silver."

in the new edition of his Handbuch der Physiologischen Necker says that he saw it at the Saleve, which is not

Optik, commencing at page 376, has been made by Prof. above the Lake of Geneva as some of our British

Everett for NATURE. The translator aims at clearness ins above the sea, and has no permanent snow near it;

rather than literal rendering, and three obvious misprints M. Folie's suggestion, that it is due to light reflected ow, must be wrong. I have seen it from the König-See,

in the paragraph on the transformation of coordinates hich I believe there is no permanent snow.

have been corrected. “Lambert's colour-pyramid ” is appearance is always to be seen under the circumstances

another name for the " cone of colour" described in Max2d, when the sky is clear and bright enough. I had well's papers and in 1074 of Everett's “ Deschanel." it in Tyndall's book, and when in the Alps I sought for nd it. I have often seen a distant approach to it pro This much-talked-of theory is a modification of Young's y furze bushes, quite near, seen against sunlight, and by

theory, which, by the choice of other fundamental sengainst moonlight. JOSEPH JOHN MURPHY.

sations, endeavours to give better explanations of what it -Ruskin somewhere describes this phenomenon.

regards as immediate facts of internal observation. It it, February 6.

assumes three elementary sensations, related to three Foraminifer or Sponge ?

different parts of the nerve-apparatus or“ visual subPer by A. Goës “On a peculiar type of Arenaceous

stance." Two at least of these physiological processes nifer from the American tropical Pacific, Neusina Agassizi,"

exhibit the opposition of positive and negative. One of been published in the “ Bulletin of the Museum of Comp.

the three “ visual substances ” gives in the condition of ,at Harvard College," vol.xxiii. No.5, in which the author

excitement the sensation of white, and in the condition is some remarkable forms dredged by the Albatross ex

of rest the sensation of black. The second gives the two in the Pacific of Central America. They are supposed to sensations of blue and yellow, which are accordingly pinifera, are of leaf-like shape, measure up to 190 mm. designated “ opposed colour-sensations." The third th, and are marked by concentric lines of growth. Their gives the other pair of “opposed colour-sensations,” red shows a stroma, consisting of fine chitinous threads, and green. But by “red” is denoted not the colour g sand and débris of shells. Without wishing to re

usually so called, but the complementary of green, which te all the various points of structure, I will only say that

is purple. n be no doubt that these forms belong to Hæckel's deep

It is possible to specify "elementary sensations” (in the tosa (see Challenger report, vol. xxxii.) from the tropical and I should think that Neusina Agassizi is identical

sense in which we have previously defined the term)

which would correspond to Hering's elementary sensations, innophyllum zonarium, Häckel. I happen to have here inger specimen of this latter species, kindly lent to me

and would be capable of giving by their combination all Manchester Museum, and its microscopic examination other colour-sensations. If we take three rectangular s me of the identity of the two forms.

axes of coordinates, x, y, z, as the edges of Lambert's rsity College, Liverpool.


colour-pyramid, x corresponding to red, y to green, and

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