THE process of “ Wear and Tear,” concerning which we had something to say in our last number, has been again illustrated in the case of Professor Huxley, who — as we are very sorry to see — has been compelled, for the time being, to relinquish work entirely. We trust that his voyage to Egypt will so recuperate him as to enable him soon to return, with all his old vigor, to the work, so valuable to mankind, which he has been engaged in performing. Meanwhile we notice with unqualified pleasure the appearance of his excellent elementary treatise on the “Anatomy of Vertebrated Animals.” Of this work, as well as of the “ Lessons in Elementary Physiology,” by the same author, we may observe that, with commendable discretion, it abstains entirely from speculation and hypothesis, confining itselt to the presentation of ascertained facts and absolutely demonstrated principles. Professor Huxley proceeds upon the soundest of methods when he thus practically insists that the student should acquire a firm knowledge of the most important facts of anatomical structure, before venturing upon the field of morphological speculation.

In point of classification, it may be observed that Professor Huxley divides the vertebrate sub-kingdom into the three provinces of Icthyopsida, Sauropsida, and Mammalia. Under the first of these provinces are comprised the fishes and amphibia; and under the second, the birds and reptiles, which are now known to be closely connected through the structures of the ostrich, cassowary, etc., on the one hand, and of the extinct dinosauria on the other. The adherence to the old classification, which included the amphibia among the reptiles, as an order parallel with the orders of ophidia (snakes) or chelonia (tortoises), is a conspicuous defect in the latest edition of Professor Rymer Jones’s generally excellent “ Outlines of the Animal Kingdom.” In future, we think, there Can be no escape from the conclusion that amphibia (frogs, tritons, etc.) are more intimately related to fishes than to reptiles. On the whole, it is very doubtful whether any improvement is likely to be made upon Professor Huxley’s triple division of vertebrate animals.

The mammals are treated under the sub-classes, now well established, of Ornithodelphia (comprising the Australian echidna and duckbill), Didelphia (comprising the marsupials), and Monodelphia (comprising all the higher mammals). The monodelphia are divided by Professor Huxley into twelve orders : Edentata, Ungulata, Toxodontia, Sirenia, Cetacea, Hyracoidea, Proboscidia, Carnivora, Rodentia, Insectivora, Cheiroptera, and Primates. In contrast with this luminous arrangement is again to be noted the classification of Professor Rymer Jones, who, still adhering to the antiquated views of Cuvier, separates the ungulata (or hoofed animals) into two distinct orders of Pachyderms and Ruminants, wrongly includes the proboscidia (or elephants) among the pachyderms, and, without rhyme or reason, divides the primates into “ Quadrumana ” and “ Bimana.” Since the apes have been proved to possess two hands and two feet, as well as man, it is quite time that this absurd designation “ quadrumana” should be dropped from authoritative treatises on comparative anatomy.

The primates are divided by Professor Huxley into the three families of Lemuridæ, Simiadæ, and Anthropidæ, or lemurs, apes, and men. The apes are divided into marmosets, American monkeys, and Old World monkeys ; and in the latter group are distinguished the Cynomorpha and Anthropomorpha. In these days of Darwinian discussion, it may be interesting to recount Professor Huxley’s condensed observations on the various relationships of the four genera of anthropomorpha or man-like apes. Of these, says Professor Huxley, “ the gibbons are obviously the most remote from man ” and nearest to the lower genera of apes. “ The orangs come nearest to man in the number of the ribs, the form of the cerebral hemispheres,” and in sundry other respects, but they differ from him very widely in the proportions of the limbs. “ The chimpanzee approaches man most closely in the character of its cranium, its dentition, and the proportional size of the arms. The gorilla, on the other hand, is more man-like in the proportions of the leg to the body, and of the foot to the hand ; further, in the size of the heel, the curvature of the spine, the form of the pelvis, and the absolute capacity of the cranium.” None of the anthropomorpha have tails.

On the other hand, it should be remembered that the gibbon, while differing from man in a greater number of points than his congeners, is nevertheless, as Mr. Mivart observes, the “ only ape which possesses that striking human feature, — a true chin.” The gibbon also approaches man in the proportions of the leg as compared with the trunk, and in the form of its bony thorax, as well as in the slight prominence of its nose. It has, indeed, been urged, with some plausibility, by Mr. Mivart, that the gibbon stands the nearest to the direct line of man’s ancestry, while the orang, chimpanzee, and gorilla are more highly developed but aberrant forms; so that, as in many other cases in the animal kingdom, the simiadæ and anthropidæ would seem to be most closely connected through the lower types of the two families. None of the speculations on this subject, however, can be considered satisfactory until we have advanced considerably further in the knowledge of the palæontology of the anthropomorphous apes.

To the venerable M. Littré, of the Institute of France, must certainly be given the credit of being one of the most indefatigable workers of the present century. Either his edition of “ Hippokrates,” completed several years ago, or his immense dictionary of the French language, now approaching completion, would by itself be regarded by most students as furnishing labor enough for a lifetime. But besides all this, M. Littré has found time to write a series of studies on the Middle Ages, on the history of the French language, and on the Positive Philosophy; besides editing the review entitled La Philosophie Positive, and contributing articles to almost every number of it. Some of the results of the medical and physiological studies in which he has so long been engaged are now published in a very interesting and instructive volume, entitled Médecine et Médecins, Paris, Didier et Cie., 1872. The book contains elaborate essays on epidemics, on spiritrappings, on mental pathology (a subject nearly akin to the preceding), on heredity, on the nervous system, on hygiene and therapeutics, and on toxicology. Under the latter head an especially noteworthy essay is the one which investigates the alleged death by poison of Henrietta, sister-in-law of Louis XIV. The circumstances attending the death of this lady are well known to the readers of Saint Simon’s memoirs. Her death being very sudden (comme foudroyée), occurring immediately after she had drunk a cup of chicory, and not being traceable to any disease then known, the inference seemed inevitable that she must have received poison in the cup of chicory. This is the impression given by the account in Saint Simon, and generally acquiesced in until the present day; and had there not been a post mortem inquiry, the results of which were uninterpret - able by the physicians who conducted it, but which were nevertheless faithfully recorded, the false impression would probably never have been corrected.

But now M. Littré, stumbling upon this problem in the course of his medical studies, has solved it in a way that amounts to complete demonstration. First cross-examining, with all the keenness of an advocate and all the sobriety of a judge, the historical evidence left upon record, in Saint Simon’s memoirs and elsewhere, he shows that it is utterly inadequate to support the hypothesis of poisoning. His next step is to seek for an alternative hypothesis, — to inquire if there is any disease now known to science which is competent to destroy its victim so suddenly (comme foudroyée) without forewarning symptoms. He finds that there is a fistula of the stomach which works in this insidious way, without causing any very notable or alarming symptoms, until all at once perforation ensues, usually upon eating or drinking something, and acute peritonitis almost instantly puts an end to life. Applying this hypothesis to the results of the post mortem inquiry, he finds that it completely explains even the minutest appearances recorded as having been witnessed by the attendant physicians. The phenomena observed were just such as must have been observed if the hypothesis of the fistula is the correct one. For the full appreciation of the singular beauty of M. Little’s inquiry, a study of the details of it is essential. No one can read it, as the author has presented it, without marvelling at the acuteness which has finally solved so difficult a problem, and at the erudition which has put each and every fact in the case, whether historical or scientific, to its proper use. However insignificant such a purely personal question in history may be in itself, nevertheless such a solution as M. Littré has given acquires great value as an illustration of the triumphs which scientific method may achieve in dealing with intricate concrete problems.

In speaking of Mr. Proctor’s “Light Science for Leisure Hours,” in our February number, we were guilty of a slight oversight with reference to the effects upon gravity of the slowly diminishing rotary motion of the earth. We should have noticed that at no time in the future can such effects be greater than they now are at the poles, where the rotation is equal to zero. So far as the past is concerned, however, our remarks — though conceived rather in levity than in seriousness — might possibly apply to the denizens of the tropics at a period when the rotation was very much greater than it now is.