chemical work in reference to their stability reappear in the text practically verbatim as they were developed by him in his own notebooks. The method of experimentation on vitamine stability as published in this paper was the outgrowth of methods previously employed by Professor Steenbock in experiments with pigeons. He should at least have appeared as a joint author of this article.

Inasmuch as the records of rat feeding, although they were part of a continuing project of the experiment station, were removed in toto from the campus with the change in staff and consequently no longer available, it had not been possible for Professor Steenbock to correlate this material for publication. E. B. HART Chairman of the Department of Agricultural Chemistry, University of Wisconsin

SCIENTIFIC BOOKS

Outlines of Comparative Anatomy of Vertebrates. By J. S. KINGSLEY, Professor of Zoology in the University of Illinois. Philadelphia, P. Blakiston's Sons & Co. Second Edition, Revised. 1917. Pp. 449.

A well-known teacher of comparative anatomy has characterized Professor Kingsley's "Outlines of Comparative Anatomy of Vertebrates" as "the best text-book of comparative anatomy in the English language." The rapid exhaustion of the first edition and the appearance of the second suggests that many other teachers share his opinion. The second edition is enlarged by the addition of fifty pages of reading matter and contains sixty more text-figures than the first edition, while the fundamental plan of the book remains unchanged. A list of Greek and Latin roots has been added to help the student to understand the meanings of the anatomical and embryological terms used.

From extended experience as a teacher of comparative anatomy Professor Kingsley has learned that a plain diet of anatomy is unacceptable to the average college undergraduate. "Boning" and "grinding" are college syn

onyms and the undergraduate does neither gladly. Anatomy therefore in the Kingsley text is made more palatable by the addition of enough physiology to give it flavor-and "meaning" in terms of function. Furthermore, an embryological approach to the study of each organ system is calculated to give a clearer conception of the fundamental relationships of the system within the organism as a whole. The text is well written with these pedagogical ends in view.

College students, however, are interested in comparative anatomy chiefly because of the bearing of the facts upon the theory of evolution in general and upon the history of the human body in particular. The text fails in general to utilize this interest. Were the bearing of the evidence upon the important problem of human phylogenesis more frequently pointed out and were much material devoid of such human interest omitted, the text would undoubtedly lose somewhat as a reference book in comparative anatomy, but it would make a much stronger appeal to undergraduates.

In its lucid and accurate descriptions and careful classification of materials the book serves as an admirable example of the scientific method. Its generalizations and interpretations, moreover, are cautious and based upon exceptional familiarity with animal structure and acquaintance with the extensive literature of comparative anatomy and embryology. The spirit of the book is open-minded and undogmatic. Errors of statement in the second edition are relative few. The statement (p. 132) that "the somatic wall of the myotome does not participate in muscle formation" needs qualification, since it is not true of all vertebrates. The retractor bulbi muscle (p. 134) is a derivative of the third and not of the first head cavity (Johnson, '13; Miss Fraser, '14). The electric organ of Astroscopus (p. 142) comes from the superior oblique muscle as well as from the muscles innervated by the oculomotorius. The "limiting sulcus" (sulcus of Monro) is not a characteristic feature of vertebrate embryos in general, as might be inferred from the descrip

tion on page 148. It should not be forgotten that the nervous character of the so-called thalamic nerve (mentioned on p. 184) has never been demonstrated, nor is it so certain that "the eye grows out from the dorsal zone of the forebrain" since that depends upon what is taken to be the morphological anterior end of the brain.

Is the conclusion (p. 191) justified that "since the vagus is a cranial nerve, its distribution to heart, stomach and lungs, shows that these structures belong to the head"? Possibly they do, but by the same token so does the tail belong to the head since this also is innervated by a branch (N. lateralis) of the vagus. In the light of what we now know regarding nerve histogenesis is it not time that the dogma of a primary, unalterable connection between nerve and its terminal organ were abandoned? Fats are spoken of (p. 220) as "hydrocarbons," although the term is used by organic chemists only in reference to oxygen-free carbon compounds. Considering the scope of the book, however, such exceptional errors are not surprising. In a field where the possibilities of divergent opinion are so many it is remarkable that the book contains so few statements to which exception may be taken.

Numerous illustrations, mostly from original sources, constitute one of the most distinctive features of the book. The unusual skill of the author as an artist is shown especially in the admirable stereograms scattered through the book, which in this respect makes another real contribution to the pedagogy of comparative anatomy. The outline drawings, however, are not always easily analyzed by the eye and might be improved by more contrast. The addition of a diagram to illustrate some of the more important fiber tracts of the vertebrate (Mammalian?) brain would aid the description on page 153. A few errors of labelling persist in the second edition. The numbers of the first and second head cavities are interchanged in Fig. 270. In Fig. 336 the right and left post-cardinals are incorrectly labelled as 66 post-cave." In Fig. 378 the two oviducts are shown as uniting in a "urinary

A Year of Costa Rican Natural History. By AMELIA S. CALVERT and PHILIP P. CALVERT. The chief object in the visit of these two entomologists to Costa Rica was a study of the dragonflies with special reference to their life-histories and seasonal distribution. However, in the preface, we are told: "Our investigations have not yet been completed and we have little to say in these pages on that technical subject. What we here set forth are chiefly our more incidental observations recorded in our diary." The first point made by the authors is in regard to the changes which will be induced by the Panama Canal. are given no hint of the factors productive of such changes or of their nature or extent. But in view of the expectations of such transformations, it is a pity that a delay of about eight years has intervened between the expedition and this publication of the general résumé of its results.

We

The authors have shown wisdom in rewriting their notes and doing away with any diary form. They have grouped their observations geographically and when several separate visits were made to any one place, these are grouped in a single chapter. As the five hundred pages of text deal chiefly with disconnected, casual notes, with annotated facts and identifications, it is impossible to offer anything like a detailed criticism. The excellent index places this information in a form readily available for reference. The volume is filled with interesting matter and adumbrates what must be the all-important scientific work of the future the direct correlation of field work with that of the laboratory and museum. As we might expect, the chief interest was insects, although plants form a close second in

amount of space. In the case of the latter, many photographs aid in familiarizing the reader with the forms of flowers and foliage. Notes on mammals and birds are almost absent. A single instance of a bird feeding upon lepidoptera was noticed. On the other hand, copious notes were made on the natives, their customs, mode of life, houses and villages. But the matter relating to dragonflies, the discovery of the various forms and the rearing of their larvæ, stand out from all the rest of the text. In dealing with this phase of research, the enthusiasm is distinctly greater, the diction more pleasing, and the treatment more thorough.

The text presents many readable descriptions of scenery and of unexpected conditions in this tropical country. Such a one is the strawberry field with its amazing amount of delicious fruit, shaded by tall rose trees. And the last chapter has a most vivid narrative of a disastrous earthquake in which the whole city of Cartago was ruined and several hundred people killed. The authors fortunately escaped with their notes and photographs. They go on to recount: "The falling wall carried with it the tumbler shelf so that the larvæ, the rearings of many months, were all killed-with one extraordinary exception. A bottle of new Cora larvæ which P. brought with him the evening before from Juan Vinas -the rarest thing we had-was found on the floor, unbroken and with the larvæ alive!"

In addition to the well-made index there are several appendices dealing with the itinerary, temperature and rainfall records, a summary of papers published in connection with the collections made on the trip, and a systematic list of plants and animals mentioned. As this latter has the page references, the contents of the volume are thus made still more available for reference. The authors are to be sincerely congratulated on having saved their incidental notes and observations from oblivion. Such work can not fail to add to any breadth of generalizations in their own more narrow field of special, intensive work, and sets a standard for other expeditions which it is hoped will often be equalled or surpassed.

7. The relative age at which breeding begins and ceases.

8. The general effect upon successive generations.

9. Sterility test; to determine whether it is the male or the female which is rendered impotent.

The number of pairs constantly under observation was 40. Approximately 20 of these pairs were restricted to a vegetarian diet and the remaining, used for control, were given the same vegetables with some form of animal food added. As soon as one of a pair died the other was remated. Or when they became too old to breed they were discarded and the cage restocked.

The results and conclusions so far reached may be summarized as follows:

If only those pairs which produce litters are taken into consideration the average number of litters per pair for the omnivorous group is 3.73 and for the vegetarian, 1.93. But when the whole group of matings are considered we find that 11.5 per cent. of the omnivorous and 55.9 per cent of the vegetarian pairs failed to reproduce. If these are considered, the average number of litters is

reduced to 3.15 and .89 per pair respectively. This is a ratio of about 3.6 to 1 in favor of the omnivorous feeders.

The greatest number of young born by a single pair is 41 in the omnivorous group and 23 in the vegetarian group. The average number of young for each mating is 15 for the omnivorous feeders and 4 for the vegetarian.

The number of young eaten by the parents is 19.5 per cent. in the omnivorous group and 35.8 per cent. in the vegetarian.

The ratio of sexes in the two groups is 113.6 males to 100 females in the omnivorous young and 107.6 males to 100 females in the vegetarian young.

The average weight (both sexes) of the omnivorous young at birth is 4.59 grams and the vegetarian young is 4 grams. A much heavier weight is maintained by both sexes of the omnivorous rats throughout their lives as shown in the curves of growth. This is shown in the following table. The retardation of growth of the new born vegetarians appears to be due to the decreased lactation of the mothers.

was born was 169 days for the omnivorous and 223 days for the vegetarian rats.

The oldest age at which a litter was born in the omnivorous group was 570 days and in the vegetarian, 600 days. The average ages were 330 and 334 days respectively. The average duration of the period of reproductive activity in the omnivorous group is thus 161 days and in the vegetarian group 111 days. The restricted diet thus appears not only to delay the period of reproductive activity, as other writers have found, but also to actually shorten the duration of this period.

Matings were made to test which sex was the cause of the failure to reproduce. Vegetarian pairs, when they ceased to reproduce, were separated. New healthy omnivorous males were mated to the vegetarian females and new healthy omnivorous females were mated to the vegetarian males. All these new matings failed to reproduce. The conclusion drawn is that a vegetarian diet produces sterility in both sexes.

It has been impossible to determine the of a continued

effect

vegetarian diet on the

The difference in appearance of the two groups is very marked. The vegetarians are smaller, have less vigor, are less active, have rougher hair and a tendency to sore eyes, while the omnivorous are the reverse in these respects.

The earliest ages at which the first litter was thrown is 90 days for the omnivorous and 119 days for the vegetarian group. Since the period of gestation is 21 days the age of sexual maturity in each of these cases was 59 and 98 days respectively.

The average age at which the first litter

19.5% 90 169 570 330 67

35.8% 119 223 600 334 97

race, as only two or three successive generations have been reared on this diet before the line of descent became extinct. We must therefore conclude that a vegetarian diet not only reduces the vitality, the growth, and the ability to reproduce, but tends to the extermination of the race.

We are expecting to have the complete paper ready for publication in the near future. J. R. SLONAKER, T. A. CARD

DEPARTMENT OF PHYSIOLOGY,
STANFORD UNIVERSITY, CALIF.