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fatigue to the presence of uric acid in the blood-in fact, considers a fatigued man to be in exactly the same condition as a gouty man. His observations, however, seem to have been very few in number, and the analyses were all made for him by a friendly chemist. Still, it is unfair to the book to regard it as a contribution to the advance of physiological science. It is really an excellent little account of the physiology of bodily exercise, and its role in the maintenance of health, by a medical practitioner. It seems to be chiefly culled from the standard French works on general physiology, and on the physiology of movement. The author has digested his materials well, and so produced a very readable and lucid account of his subject. For a book of its class, it is remarkably free from mistakes, though physiologists might not agree with him in his account of the production of breathlessness or the causation of gout.

The style is simple, and the book is well adapted for popular use, and ought to find favour with our exerciseloving countrymen.

E. H. S.

Boilers-Marine and Land. By Thomas W. Traill, F.E.R.N., M. Inst.C.E. Second Edition. (London: Charles Griffin and Co., 1890.)

THIS volume is a second edition of a work noticed in these columns last year. It was then a pleasure to express the opinion that the work would be useful to all connected with this particular branch of mechanical engineering. The author has found it necessary to extend the tables of scantlings, &c., from 160 to 200 pounds pressure per square inch. This in itself is sufficient evidence of the continued increase of steam pressures used in marine and stationary engines-probably the only practicable direction in which greater economy of fuel is to be obtained. These increased steam pressures have also the advantage of diminishing the gross weight of machinery on board ship.

The greater use made of mild steel by engineers generally is interesting, considering the fight the steel manufacturers had a few years ago to get it used at all in place of iron for many purposes. Mr. Traill observes that, "notwithstanding the peculiarities of mild steel, it is a material which may be used with safety and advantage, if proper precautions be taken and due consideration given to these peculiarities; possibly it has fewer infirmities than iron; and there can be no doubt that it is a better and more serviceable material for general use in the construction of boilers." This is the experience of most engineers intimate with the general behaviour of the material when being worked up into boilers and other constructions. To the many tests and safeguards specified to prevent the use of a brittle and bad steel in any erection is due the present excellence of this material, nor should they now be in any way relaxed, for to accept material, either iron or steel, on any particular brand is a mistake. The general utility of the work has been increased by

the addition of other matter and tables. The volume
cannot fail to be of very great use to engineers. It is
nicely printed, got up in a handy size, and strongly yet
pliably bound.
N. J. L.
Edited by
(London:

The History and Pathology of Vaccination.
Edgar M. Crookshank, M.B. Two Vols.
H. K. Lewis, 1889.)

THE arguments adopted in this work belong to a mental attitude identical with that displayed by anti-vaccinators in their clamorous treatment of the subject. They are sophistical from beginning to end, and even as a book of reference the volumes are not without drawbacks.

Firstly, the argument is that cow-pox is to be regarded as akin to syphilis rather than to small-pox, and that therefore cow-pox is no protection against small-pox. On this hypothesis ulcerated arms sometimes occurring after vaccination are to be regarded as reversions to type,

rather than as due to the ill-treatment by over-anxious mothers not content to let Nature alone in her progress towards recovery. Having assumed that vaccination is no protection against small-pox, the book goes on to show that the only means we have of controlling the devastations of this disease is by attention to sanitary arrange ments and by isolation, perhaps combined with judicions inoculation. The latter, the book assures us, is a more scientific procedure than the inoculation of cow-pos Next, the author is very angry with Jenner for calling vaccinia, cow-pox" or "variola vaccinia." To this stroke of dexterity by Jenner is to be attributed, says Prof. Crookshank, all the credit that vaccination has attained; thus for a single happy thought Parliament gave Jenner £30,000 as a consequence of his conceit, and England has been made to submit to the most tyrannical of laws.

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This carping at the pioneer of new knowledge, an more especially at those forecasts of his which necessary could only be verified by the lapse of time, is certainh not calculated to shake the faith of those who now fully comprehend not only the immense value of vaccination. but also the small amount of mischief which it has eve done.

The best that can be said for Prof. Crookshank's work is that it is well published. The printing is bold and clear, and the lithographs, such as they are, wel reproduced.

Vol. ii. contains reproductions of original papers, most if not all of which are out of print, and cannot now be obtained except at fancy prices.

Had Prof. Crookshank been satisfied with editing these and had he refrained from expressing his opinions, we should have been grateful to him. The book does no pretend to be a practical work on the subject of which it treats; and for the rest it might have been compiled by the average anti-vaccinator. ROBERT CORY.

LETTERS TO THE EDITOR.

[The Editor does not hold himself responsible for opinions 13 pressed by his correspondents. Neither can he undertak to return, or to correspond with the writers of, rejecte manuscripts intended for this or any other part of NATULE No notice is taken of anonymous communications.]

The Transmission of Acquired Characters.
and Panmixia.

I SUPPOSE that a correspondent has no claim to limit the scope of a discussion in such a journal as NATURE. At the same time I feel it to be a rather severe burden when I am caller upon to expound, in answer to one letter after another, the meres common-places of the subject under discussion, and to retail in this place the substance of books like Weismann's "Essay, and Wallace's "Darwinism" (to which the attention of you readers has been already drawn by reviews), not to mention the "Philosophie Zoologique" and the "Origin of Species." b seems to me that there might be interest and profit in opening your columns to the statement of newly observed cases which seem to tell in favour of either the Lamarckian or the ant Lamarckian theories, or to novel criticisms of any cases which citation of familiar exploded cases," and the reiteration of have already been discussed elsewhere; but surely the repeated arguments and beliefs which have long since received attention is not fair to the writers who have dealt with these cases and these arguments in admirable treatises which are well known (I am happy to think) to nearly all serious students of these questions

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When I saw the distinguished name of Mr. Herbert Spencer at the end of a letter in your issue of March 6, I anticipated some real contribution to the discussion as to whether acquired characters are transmitted or not. Mr. Spencer some few years ago expounded his convictions in favour of Lamarck in one of the monthly reviews. His present letter is not only diappointing, but is unfortunately likely to mislead the uni formed. Mr. Spencer states what we all know, viz. that Mt. Darwin considered that the effects of habit and of ase and

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disuse are transmitted from the affected generation to its offspring. He refers by chapter and page to the instances which Mr. Darwin considered as examples of the transmission of the effects of habit or of use and disuse. He then says: Clearly the first thing to be done by those who deny the inheritance of acquired characters is to show that the evidence Mr. Darwin has furnished by these numerous instances is all worthless." entirely disagree with this way of putting the matter. It is not necessary to show that anything Mr. Darwin wrote was worthless," but it is necessary to show that certain facts cited by Mr. Darwin admit of another interpretation or explanation than that which he gave to them. Naturally those who have taken up the anti-Lamarckian position have done long ago what Mr. Herbert Spencer says is the first thing for them to do. Of course the cases cited by Darwin were the first to be dealt with. It is extremely unfortunate that Mr. Spencer has not come across the work in which this is done. Otherwise, instead of a well-meant direction from Mr. Spencer as to what we ought to do, we might have the advantage of reading what he has to say after considering what has been done. It is seven years since Prof. Weismann published his essay on heredity; last spring this and other essays appeared in English under the auspices of the Clarendon Press. In that particular essay Darwin's cases are dealt with at length. Am I to reproduce Prof. Weismann's essay or a précis of it in this letter? Will not Mr. Spencer and others who are interested in these matters read Weismann's "Essays"? I think that those who will take the trouble to do so will see that Mr. Spencer's injunction was superfluous.

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It is, however, apart from other branches of the question, important that a correct appreciation of Mr. Darwin's position in this matter of the "transmission of acquired characters should be arrived at. Mr. Herbert Spencer's letter is, I think, likely to produce an erroneous conception on this matter. know from his letters published since his death that Darwin held the "Philosophie Zoologique" to be "veritable rubbish ""extremely poor; I got not a fact nor an idea from it." The notion that his own view was a modification of Lamarck's appeared to Darwin absurd. The "obvious view" was propounded by Lamarck, he says, "that if species were not created separately they must have descended from other species, and I can see nothing else in common between the Origin' and Lamarck." This was Mr. Darwin's attitude of mind to Lamarck's theory, and the cases in which he attributes importance to the effects of use and of disuse, and to acquired habit, and consequently to the Lamarckian principle of the transmission of acquired characters, are clearly to be regarded as concessions or admissions on his part, given with increasing generosity in the later editions of the " "Origin"; but always treated as of quite subordinate importance. It is not going too far to say that Mr. Darwin never troubled himself very much with the question as to whether acquired characters are transmitted or not. It was the object of his works to show that the main effective principle in the origin of species is the natural selection in the struggle for existence of congenital characters. He explicitly states that he believes other causes to be at work; one of which at least, viz. sexual selection, he himself investigated at length. It must be remembered that no evolutionist in Darwin's life-time had prominently challenged the truth of the Lamarckian assumption that acquired characters are transmitted. For Darwin it was sufficient to show that, granting such a process to take place, it would not account for much; he was content to accept it as a subordinate factor. His view is best stated in his own words in the "Origin of Species": **On the whole we may conclude that habit, or use and disuse, have, in some cases, played a considerable part in the modification of the constitution and structure."

Whilst it is true that Mr. Darwin in various parts of his works alludes to cases which he interprets as due to the transmission of characters acquired by parents through habit, use, or disuse, it is obvious, when we read what he has to say in each case (as in the examples cited by Mr. Herbert Spencer), that he preferred, where it occurred to him another interpretation. Thus, after referring to the wings of the logger-headed duck and the domestic Aylesbury duck as dwindled by the transmission in successive generations of the effects of disuse, he interposes his own explanation by natural selection of the wingless beetles of Madeira, prefaced by the words: "In some cases we might easily put down to disuse modifications of structure which are wholly or mainly due to natural selection." refuses to regard the defective anterior tarsi of dung-beetles as

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due to inherited mutilation, though he supposes they may have become deficient through disuse. He regards the defective eyes of cave-animals as due to the inheritance of the effects of disuse. I can scarcely doubt that, had it occurred to him, he would have preferred an explanation similar to that given by him of the wingless island beetles, viz. that a natural selection of animals with defective eyes takes place in a cave; since ultimately only those remain in a cave and breed in it which, in the course of their wanderings, are unable to see the faint light which penetrates to a great distance from the mouth, and must guide all those but the congenitally blind or weak-sighted to the exterior. The defective eyes of moles are ascribed by him not merely to disuse but to the selective action of inflammation. The case of the silkworm caterpillars with defective instincts (which is one of those given by Mr. Spencer) does not appear to me to bear on the present question. Of acquired characters, other than those due to disuse, Mr. Darwin accepts very few as being transmitted. He accepts the statements of Brown-Séquard as to the transmission of the effects of mutilations of guinea-pigs only so far as to "make us cautious in denying such transmission." He regards the dislocation of the eye of flat-fishes as due to the inheritance in successive generations of an increasing displacement caused by muscular effort. Besides these two instances (noted by Mr. Spencer) there is one other prominent passage in which Darwin asserts his belief in the inheritance of an acquired character which is not merely the result of disuse. I am anxious to separate those cases which Darwin speaks of as "due to the effects of disuse," for a reason which will appear below. The additional passage not noted by Mr. Spencer is this ("Origin of Species," p. 206, sixth edition):-"If we suppose any habitual action to become inherited-and it can be shown that this does sometimes happen - then the resemblance between what originally was a habit and an instinct becomes so close as not to be distinguished. If Mozart, instead of playing the pianoforte at three years' old with wonderfully little practice, had played a tune with no practice at all, he might be truly said to have done so instinctively. But it would be a serious error to suppose that the greater number of instincts have been acquired by habit in one generation and then transmitted by inheritance to succeeding generations. It can be clearly shown that the most wonderful instincts with which we are acquainted—namely, those of the hive bee and of many ants-could not possibly have been acquired by habit."

The cases of the epileptic guinea-pigs, the eyes of flat-fishes, and of some acquired habits, have been discussed by Weismann and by Wallace. I will not now allude further to those classes of cases. But I am anxious to draw attention to the special subject of the "effects of disuse" as set forth by Mr. Darwin. This phrase is not only used by him in regard to special instances, but, in treating of the large subject of rudimentary organs, he frequently refers to the "effects of disuse." says, "It appears probable that disuse has been the main agent in rendering organs rudimentary" ("Origin," p. 401).

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Now I am anxious to point out three things in regard to the "effects of disuse." (1) There are other possible effects of disuse of an organ than the dwindling of that organ in one generation, and the inheritance of the organ in a diminished size by the next generation. (2) The anti-Lamarckians attribute a very great effect to disuse, although they do not attribute to it the particular result which Lamarck did. (3) The particular way in which, according to the anti-Lamarckians, disuse acts so as to lead to the dwindling or complete loss of the disused organ has been called by Weismann by a convenient name-"panmixia." The doctrine of panmixia is already indicated by Darwin himself, and in view of this fact we must suppose that, when he attributed the loss or dwindling of an organ to "disuse" or the "effects of disuse," he did not necessarily (though probably he frequently did) refer to the Lamarckian modus operandi of disuse, but may very well have had in mind the results which are a tributed to disuse by the anti-Lamarckian doctrine of panmixia.

The doctrine of panmixia is this. When there is no longer, owing to changed conditions of life, any use for an organ, it will cease to be the subject of natural selection. Consequently all possible variations of the organ will have (so far as the now lapsed use of the organ is concerned) an equal chance. Amongst the possible variations there will be the variation in the direction of increased size, and its exact complement-the variation in the direction of diminished size. Prof. Weismann has stated briefly that this equal survival of all possible variations must lead to the

dwindling and ultimate loss of the organ. I would, however, venture to supplement what he has said by the following: viz., given the state of panmixia, it is apparent that variations in the direction of excessive size will be injurious-both as taxing the nutriment of the organism, and often as mechanical encumbrance. On the other hand, variations in the direction of greatly diminished size will be advantageous, as causing a diminished tax on the resources of the organism. Now it is a demonstrable fact that excessive variations in both directions do naturally though rarely occur-probably more often than is supposed, since we do not see all the young born. If the variations in the direction of excessive diminution of a useless organ (as, for instance, tailless cats or hornless sheep) survive as being less taxed-whilst the complementary variations in the direction of excessive size tend in the struggle to die without reproducing, owing to their awkwardness and their relatively greater burden in life-then it is clear that panmixia may lead rapidly to the dwindling and eventual extinction of a disused organ without any transmission of acquired parental character. The fact that there is no use for an organ-or, in other words, the "effect of disuse"-is that the congenitally small varieties of the organ survive, and are even favoured in the struggle for existence. Whilst Weismann has the merit of having insisted on a form of his doctrine as the effective reply to those who argue in favour of Lamarck's theory of the transmission of acquired qualities from instances of" disuse," it is yet the fact that Mr. Darwin himself recognized and formulated the doctrine of panmixia in the last (sixth) edition of the "Origin of Species," published in 1872; and he even went further than Weismann, for he associated the principle of the economy of material with the principle of the cessation of selection. It is therefore, it seems to me, not at all improbable that when Darwin refers, here and there throughout his works, to a reduced or rudimentary condition of an organ as "due to disuse," or "explained by the effects of disuse," he does not necessarily mean such effects as the Lamarckian second law asserted and assumed (though often he does appear to mean such); but he may mean, and probably had in his mind, the effects of disuse as worked out through panmixia and economy of growth.

The passages in Darwin which seem to me to have been missed or neglected by those who think panmixia altogether a new idea are as follows:

(1) "If under changed conditions of life a structure before useful, becomes less useful, its diminution will be favoured for it will profit the individual not to have its nutriment wasted in building up a useless structure." After an example in point from the group of the Cirripedia, Darwin conttinues: "Thus, as I believe, natural selection will tend in the long run to reduce any part of the organization as soon as it becomes, through changed habits, superfluous, without by any means causing some other part to be largely developed in a corresponding degree" ("Origin of Species," sixth edition, p. 118).

(2) Organs, originally formed by the aid of natural selection, when rendered useless, may well be variable, for their variations

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no longer be checked by natural selection. . . . It is scarcely possible that disuse can go on producing any further effect after the organ has once been rendered functionless. Some additional explanation is here requisite, which I cannot give. If, for instance, it could be proved that every part of the organization tends to vary in a greater degree towards diminution than towards augmentation of size, then we should be able to understand how an organ which has become useless would be rendered, independently of the effects of disuse, rudimentary, and would at last be wholly suppressed; for the variations towards diminished size would no longer be checked by natural selection. The principle of the economy of growth explained in a former chapter [cited in quotation No. 1], by which the materials forming any part, if not useful to the possessor, are saved as far as possible, will perhaps come into play in rendering a useless part rudimentary" ("Origin of Species," sixth edition, PP. 401-402).

I had written thus far, and intended to finish this letter by asking if the anti-Lamarckians are not really carrying out the spirit of Darwin's doctrines, although not the absolute letter, when I received your issue of March 13, containing a long letter from Mr. George Romanes, headed "Panmixia." In that letter Mr. Romanes, whilst amending (as I have done above) Prof. Weismann's statement of the principle of panmixia, makes the definite assertion that "it is remarkably strange that this principle should have been overlooked by Mr. Darwin."

Probably your readers will be as much astonished as I wal when they read the extracts I have above given from the "Origin of Species" by the side of Mr. Romanes's letter.

After dismissing Mr. Darwin, Mr. Romanes proceeds to say: "In this connection, however, it requires to be stated that the idea first of all occurred to myself, unfortunately just after the appearance of his last edition of the Origin of Species."

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Now, inasmuch as the idea in question is (as I have showe above) formulated in the last edition of the “Origin of Species," I confess that I do not think it requires to be stated that the idea occurred to Mr. Romanes shortly after the publication of that work. What more natural? The idea occurred to me also shortly after the passages above quoted from Mr. Darwin were published. It certainly never appeared to me "unfor tunate that this was the case, and I cannot see where the mis fortune comes in in regard to Mr. Romanes. As soon as the matter had taken root in his mind, Mr. Romanes published in NATURE, March 12, April 7, and July 2, 1874, an exposition of the importance of the principle of cessation of selection as a commentary upon a letter by Mr. Darwin himself (NATURE, vol. viii. pp. 432, 505) in which Mr. Darwin had suggested that, with organisms subjected to unfavourable conditions, all the parts would tend towards reduction. Mr. Darwin, with his usual kindly manner towards the suggestions of a young writer, gives at p. 309 of vol. ii. of " Animals and Plants under Domestication (second edition), Mr. Romanes's view, "as far as it can be given in a few words." The view, as it there appears in Mr. Darwin' words, is certainly not the same as that which Mr. Romanes la expounded in NATURE of March 13, 1890 (p. 437), and ne represents what Mr. Darwin had been able to gather from Mr Romanes's letters to NATURE of 1874, it is not at all surprising that Mr. Darwin did not recognize any resemblance between and his own statement, viz. that "the materials forming any part, if not useful to the possessor, are saved as far as possible," thus "rendering a useless part rudimentary." Whether the is, or was, Mr. Romanes's view or not, it is Darwin's, and is the essence of the anti-Lamarckian view of the effects of disuse. March 15. E. RAY LANKESTER.

Exact Thermometry.

SHORTLY after the publication of my second letter on this subject (NATURE, January 23, p. 271) I received a letter from M. Guillaume, who very kindly called my attention to a pare by Prof. J. M. Crafts (Comptes rendus, xci. p. 370), in which the "plastic theory" is discussed. Prof. Crafts states that he has subjected thermometers to prolonged heating at 355°C.. under various conditions as regards pressure, the internal pres sure being in many cases considerably greater than the external. but that there was invariably a rise of the zero-point. The experiments were carried out in very much the same manner & that described in my first letter (NATURE, December 19, 188, p. 152), and had I known at the time of the earlier work et Prof. Crafts, I should of course have referred to it. Prof. Crafts also describes and quotes experiments with air-thermometers the temperature in one determination by Regnault being as high as 511° C., and the internal greater than the external pressure: in every case the bulb diminished in volume. From these re sults, Prof. Crafts concludes that it is not proved that pressure plays any part in the contraction of the glass.

My experiments can therefore be regarded as little more than confirmatory of the earlier work of Prof. Crafts and others, bat as such it may be worth while to give the results. The method adopted was fully described in my first letter, and it is therefore only necessary to repeat that in thermometer A the external pressure exceeded the internal, while in thermometer C there was considerable internal pressure, but no external. According to the plastic theory, therefore, the zero-point of A should have risen, while that of C should have fallen. The results previously described were regarded as insufficient by Prof. Mills, and 1 have therefore continued the heating for a much longer time. I have also made similar experiments with two other thermo meters belonging to the same batch, at a temperature of abon 356°, the thermometers being heated in the vapour of boiling mercury. During the first three hours, the two thermometers a and b were treated in precisely the same manner, as regarde pressure, as A and C, and it will be seen that the zero-point b showed a slightly greater rise than that of a. Afterwards, air was admitted into thermometer a, so that there was an excess of internal over external pressure in both thermometers, but the excess was greater by one atmosphere in & than in a

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I may also mention that M. Guillaume has informed me that M. Tonnelot has heated several thermometers to 450°, and that, notwithstanding a considerable internal pressure, a rise of the zero-point was observed in every case.

All these results seem to lead unmistakably to the conclusion that pressure has little or no effect on the rise of the zero-point. Three questions remain to be discussed

(1) Would the total rise of the zero-point be different if two similar thermometers were subjected to sufficiently prolonged heating at different temperatures? At first sight, it would certainly appear that at 356° the total rise with my thermometers must be greater than at 280°, but I do not feel satisfied that the proof is sufficient. If we map the observations of zero-point against the time of heating, curves are obtained which appear as if they might become horizontal after a few weeks or, possibly, months; but if, instead of the actual times, we take their logarithms-as in the diagram-as abscissæ, there is no appearance of an approach to the final state at either temperature. But while at 356° the curve has become almost a straight line, at 280° there appears to be an increasing tendency towards the vertical direction. I do not for a moment argue that the curves indicate that the maximum rise would be the same at both temperatures if the experiments were carried on for a sufficiently long time; but, at the same time, I do not think that they afford any convincing proof that the total rise would be different. The results merely tend to increase my scepticism as to the value of the determination of the maximum rise at o° obtained by extrapolation of the curve constructed from observations at that temperature. It does not appear to me that it would be justifiable to extrapolate these curves at all, and I am afraid that they do not throw much light on the total rise of zero-point at either temperature. Very much more prolonged heating would be necessary before arriving at a definite conclusion.

(2) With regard to the causes of the contraction of the bulb, I have no hesitation in admitting that-as shown by M. Guillaume-the removal of the condition of strain caused by the

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(3) Lastly, there is the question raised by Mr. Tomlinson, as to whether repeated heating and cooling between wide limits of temperature is more effective in raising the zero-point than prolonged heating at the higher temperature. The points reprethe individual observations, fall very fairly on the curves

constructed from them, and do not seem to indicate any noticeable difference in the effect of long or short heating. The results can hardly, however, be regarded as decisive. University College, Bristol, March 1.

SYDNEY YOUNG.

Foreign Substances attached to Crabs.

SINCE Hyas is one of the most abundant Crustaceans found off the east coast of Scotland, Mr. Holt must adduce considerably more than two instances before it can be admitted that the attachment of Simple Ascidians to this crab is at all a usual Occurrence. If it is, I should still be anxious to inquire whether the crab does not-in spite of the apparent difficulty of the operation-place the Ascidians upon its back with its own nippers. I may cite Gosse's well-known experiment with Pagurus prideauxii and Adamsia palliata, described in his "Year at the Shore," for the purpose of analogy. But Mr. Holt will find a case, probably quite similar to that which he mentions, in Bell's "Stalk-eyed Crustacea." Two specimens of Hyas araneus were found with oysters attached to their backs, that on the larger crab being three inches in length, and five or six years old, probably a much more "serious incubus" than Mr. Holt's Tunicates. The crab's carapace was but two and a quarter inches in length. Hence, despite the world of weight upon its shoulders," Mr. Thompson concluded that "the presence of this oyster affords interesting evidence that the Hyas lived several years after attaining its full growth." Probably the larvæ of the oysters, and of the Ascidians also, happened to alight upon the crabs at the end of their free-swimming existence, although six or seven years seems to me to be a remarkably long age for a Hyas.

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Barnacles upon the backs of Maia, Carcinus, &c., are also due to the same, as it were, accidental cause.

But, whatever the explanation, these exceptional cases do not alter the fact that the foreign bodies found upon Hyas are usually fixed there by the crab itself. The specimens I have seen have been covered with fragments-not living colonies-of Algæ, Hydroids and Polyzoa, which are fastened by the hairs of the crab's carapace and legs exactly as in Stenorhynchus, and in this crab the process of attachment has been frequently observed here and accurately recorded.

At the same time I by no means hold that the two groups which were defined in my previous letter are absolutely marked off from one another. The hermit crabs make use of both methods of protection. Bits of Sponges may frequently be seen upon the carapace of Maia, Stenorhynchus, and Inachus, and I have occasionally found colonies of Leptoclinum and Didemnum upon both Maia and Inachus. In these cases the inconspicuous appearance is not lost, but the attachment of small Sponges and Didemnids is probably an additional protection against the numerous night-feeding fishes, which hunt their prey by the senses of smell and touch.

As to the inedibility of Tunicata, I did not-as Mr. Holt states "assume" it. I have experimentally found it to be a fact (as I stated in my letter) that the odour and taste of "Tunicata, and especially Compound Tunicata," are almost invariably sufficient to prevent fishes from eating them. Exceptions do not disprove the rule, and it is quite possible that Pelonaia is not distasteful. But this is not established by a few specimens having been taken on one or two occasions from the stomachs of Cod, Haddock, and Dab; and although Mr. Holt quotes Prof. McIntosh as speaking of the "abundant occurrence of Molgula arenosa in the stomachs of Cod and Haddock, he will find upon reading Prof. McIntosh's words again, that they are open to a different interpretation.

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In my previous letter I omitted to mention that a species of hermit crab also, Eupagurus lucasii, takes advantage (regularly?) of the distastefulness of Compound Ascidians. Mr. Harmer has, with much kindness, examined for me a specimen in the Cambridge Museum. The crab inhabits a univalve which is covered with Distaplia magnilarva.

Mr. Holt's statement that "Actinia mesembryanthemum is certainly a favourite food of the Cod" is so astonishing that I hope he will adduce the evidence for his assertion. Mr. Brook had not found this to be so when he reported upon the food of this fish for the Scottish Fishery Board, and indeed only the youngest Cod ever frequent the tidal waters to which A. mesem bryanthe num is confined. Further, although Pagurus bernhardus, when not associated with an Anemone, is very frequently found in the stomachs of Cod and Haddock, I do not know a single instance of its having been found in the stomachs of the same fish when associated with one.

I am informed by Mr. Poulton that, in a work which is shortly to appear, he has included such animals as Stenorhynchus and Caddis worms, which disguise their appearance with foreign bodies simply in order to escape identification by enemies, in a

group to which he gives the very convenient name cryptic." Animals which trust rather to the offensive than t the inconspicuous character of the foreign bodies with wh they associate themselves he terms "allosematic" ( sign).

It is obvious that the allosematic method of protection is al but perfect, since it is largely free from the loss due to exp mental tasting attendant upon the method of a purely warning appearance ("autosematic"). WALTER GARSTANG. Plymouth, March 21.

Sea-bird Shooting.

Is it not time that something more was done to stop the wholesale slaughter of our sea-birds? During the past water the havoc has been terrible, and unless some restraint is inv we may expect before long to find our shores denuded of the white wings. When the birds had no value, there was a iz though a wide one, to their destruction, because of the 'ce 2 killing them; but recently a large demand has sprung up f their skins, and an organized traffic is now carried on in the

carcases.

The shooter gets from threepence to sixpence per bird from the amateur dealer, and for the sake of this paltry sum (surely the birds are worth more to us alive than this!) there is not a sporting lounger on the coast who can possess himself of a guy who does not kill every bird which can be reached either the shore or from a boat. The gulls are pursued, I am to even as far as the Dogger Bank.

The beautiful kittiwake is the greatest sufferer. One of the dealers boasted to me the other day that he had passed "scares ten than nine thousand dead birds through his hands th season, chiefly kittiwakes." He added that he had got 804 carcases in one batch from one sportsman.

From inquiries, I judge that this person's trade represen about one-third of the dead birds which have been sent away ima our little town this season. I know the traffic is carried on D other points, and no doubt this is but an example of what u going on all round our coast. When we consider that the r cases which can be secured represent only a fraction of the bird's killed or injured, we gain some idea of the extent of the me chief. Indeed, during the past month it has been possible to take a long walk along our shore without seeing a single sca gull. Who wishes to see a blank seascape?

Now, surely, we all have equal rights in these graceful birds and the numerous class who love to see them alive deserve as much consideration as the mischievous minority whose plessure it is to destroy them! It is not as though these latter were worthy persons, compelled to a cruel employment for their daily bread: they are, on the contrary, nearly all of a class who deserve no sympathy-of a comfortable class who) verily believe, would shoot their next-door neighboars if they could do so with impunity, and could dispose of the carcases Just imagine the new variety of "sport" which one of thes described to me not long ago! He said you could catch u gulls at sea by baiting a floating fishing-line with liver, and e this way, though you did not get quite so many as with a gun, you had far better fun, especially from the kittiwakes, as thei are wonderfully game, and, when they feel the hook. flacker about and scream like a child"!

Is it too much to ask that our Legislature, which has spent s much time in the past on laws in the interests of the so-calle "preservers" of game, will do something, and that speedily, in the interests of those who would fain be truly preservers of the se birds? At least they should extend the protection afforded to "game" to these noble birds, and order that those who shou them shall pay a heavy license for their despicable sport, an those who deal in the dead carcases a still heavier.

And nothing in this matter must be left to local authorities. In seaside places self-interest vitiates the sentiment on this ques tion. The fisherman finds it easier to earn money by letting his boat to the "sportsman" than by his legitimate productive dustry; the tradesman fears to lose these men's custom; and the gentry, mostly supporters of " sport," are perhaps not sorry to have such an excellent safety-valve for guns which might other wise poach on their preserves; and besides, there is in Yorkshire a semi-political aspect to the matter. Thus it has happened that of late years the clause in the (so far as it goes) excellent ~ Sesbirds Preservation Act" of 1869, which permits a lengthening of the close time under certain conditions, has been rendered

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