With birds, the presence of a fovea seems to be the rule. In fact, the domestic chicken is thus far the only exception. Many birds have a fovea and band-like area, while some have two fovea and a band-like area connecting them.

In reptiles, the number of species provided with fovea or simple area are more nearly equal, while with amphibians and fishes, the area has frequently not been seen, and the fovea is only seldom observed.

The area centralis varies greatly in form and extent in different animals. It varies from the round form of small extent found in the cat and the weasel to the band-like form found in the horse, sheep, rabbit, frog, etc., which extends horizontally across the retina.

In the case of the fovea we also find a variety of forms and positions. In some animals it is situated on the nasal side of the entrance of the optic nerve (fovea nasalis), while in others it is on the temporal side (fovea temporalis). According to Müller, in the former case we have monocular vision, while in the latter we have binocular vision. In form it varies from a mere dot-like impression, as in some lizards, to a well marked funnel-like pit in most birds, especially crow, bluejay, robin, etc., and to a trough-like depression in the crocodile which extends horizontally across the retina. Two foveæ have been found in some birds, as in swallows and terns, in which case the fovea nasalis is very near the centre of the retina, and has to do with single vision. It is also larger and deeper than the fovea temporalis, which is situated near the ora serrata and functions in double vision. According to Chievitz, the tern has not only two fovæ, but a trough-like fovea connecting them, and the goose, duck and gull have a round fovea and a bandlike area.

A great difference exists in the different vertebrates when their ability for acuteness of sight is considered. It varies from the most perfect sight found in man (and possibly in birds

H. Müller, Ueber das Vorhandsein zweier Fovea in der Netzhaut Vieler Vogelaugen-Zehender, Klinische Monatsblätter, Sept., 1863, p. 438-440; or Anatomie und Physiologie des Auges, p. 139, 142–143.

'J. H. Chievitz, Ueber das Vorkommen der Area centralis retinae, Archiv. f. Anat. u. Entwick., 1891, p. 324.

also) where exceedingly fine discriminations are possible, to the limited visual power found in other animals, where only an area centralis is present. Though acute vision and a fovea have always been associated, still we cannot, at present, say that the animals which do not possess a fovea are not able to see acutely. In order to make clear the relation of sight to the habits of the animal, a much more careful observation of its visual habits, and the histological arrangement of the retinal elements will be necessary.

EDITOR'S TABLE.

-THE Antivivisectionists have been endeavoring to get a consensus of opinion on the utility of vivisection, by circulating blanks for signatures, which are attached to a few alternative opinions on the subject in point. The alternatives, excepting those expressing an unconditional affirmative and negative, were not sufficiently precise or well stated to satisfy persons of moderate views, so that it was necessary to amend them more or less to express such opinions. In the summary of the results thus obtained, the antivivisection managers omitted most of these moderate views, and only gave to the public the two extremes. The circulars were also very injudiciously distributed, as a majority of them went to persons unfamiliar with the work of scientific research, as clergymen, etc. The only persons who have a practical knowledge of the subject are original investigators in the natural sciences, physiologists and physicians. The opinions of other persons must be mostly formed at second hand.

As a body of men, those above referred to are at least as humane as any other class in the community. Their business is to relieve suffering, and they are not insensible to those of the lower animals. Naturalists, as a body, are probably more humane in their feelings towards animals than any other class in the community. Nearly all of these meu are, however, well convinced not only of the propriety, but of the necessity of vivisection. It is the only method of attacking many difficult problems of physiology. It is the basis of our knowledge of the functions of the human organism, which is itself the first essential to the control of human disease and human suffering. The autivivi

sectionists are, unwittingly, doing what they can to sustain ignorance and to prevent the relief of human suffering. They are sacrificing their fellow beings, their relatives and their friends, in preference to a few of the lower animals. Men, women and children may suffer and die; white rabbits, guinea-pigs and dogs may live. Such logic is like that of the Spanish Inquisitors, who tortured human beings under the belief that they served God and the cause of religion in so doing. There is, however, less excuse for the antivivisectionists, since knowledge is more widely distributed now than then, and the great utility of vivisection has been demonstrated over and over again.

The six national scientific societies to meet during the holidays in Philadelphia will probably express their views on this subject, and it may be confidently expected that these will accord with those of science the world over.

Intelligent people are best deceived by intelligent frauds. A fraud in order to succeed in the United States must make pretensions to superior knowledge. The alleged or actual graduate of medicine who desires to be a fraud has a pretty good field in this country; and his successes are ever with us, in spite of the opposition of the many true men of that profession. The scientific fraud has not yet developed very largely, as there is no money to be made by pretense in this direction. In fact this species of the genus is not generally a person of evil intentions, and errs chiefly through an active imagination, and perhaps sometimes through a tendency to megalomania.

We are moved to these remarks by reading an article in the December number of a Chicago Journal called Self Culture. On p. 587 we read; "Examination of the brain of such an idiot before its education has begun, shows but few brain cells, and a few nerve fibres connecting them. And when a postmortem has been made upon the child that was once an idiot but that has been lifted up by long years of patient training to citizenship in the moral and rational sphere in which we live and move, such a postmortem shows that an infinite number of braincells have been created de novo; that fibers becoming necessary have appeared, to connect such cells, centers of sensation and emotion and thought."

Now the author of this paragraph should refer us to the published articles which describe the removal of the brains or parts of brains of idiotic children for sectioning and microscopic investigation, and the subsequent replacement of these organs or parts of them in the crania of the children in order that they may undergo the "long years of

patient training" which follow. of the operation, and the name of the operator and that of the institution where he operates. Some grown persons might desire to secure his services, and almost everybody could point out some one else, to whom they think such a course of treatment would be useful. Some peculiar conditions might be found which it would be desirable to remove permanently, and so save the "labor of long years" etc.

We would like to know the technique

The editor of the Journal on page 609 stimulates our curiosity further by saying that "Professor Elmer Gates, a psychologist who has for several years been making elaborate studies both in Washington and Philadelphia, has added not a little to our knowledge of the developments of the brain and the relation of particular parts of the brain to thought and emotion and the use of particular parts of the body." The view indeed is not new, but the confirmation given by Prof. Gates researches is very interesting" He then quotes language from Dr. Julius Althaus as to the supposed seat of mental activity in the brain, which embodies a general statement of the little knowledge we have on the subject. The question naturally arises as to the alleged researches of Dr. Gates, and the extent to which they have confirmed our hypotheses on this subject, and if so, as to where they were published? The editor does not tell us. This is a pity, for assertions without authority are useless to science. Is there any connection between these researches and the alleged vivisection of idiots recounted in the article we first quoted? The name signed to the latter is not that of Dr. Gates, so we are quite in the dark. A journal which publishes an article by Sir Wm. Dawson, and writes up the Universities, ought to give us more light no these wonderful researches.

-IT is again proposed that the American Association for the Advancement of Science meet in San Francisco in the near future. The Board of Supervisors of that city are said to have extended an invitation to visit the city in 1897. The Association has had many such invitations, and they would have been accepted had the railroad authorities been willing to place their rates within reach of the members. The authorities of San Francisco have, however, this time included in their invitation the British and Australian Associations, and we are informed that the British members will have free or nominal transportation via the Canadian Pacific R. R. It is said that the Dominion of Canada will make an appropriation towards defraying their transportation expenses. Perhaps our Congress would be willing to make an appropriation for securing the transportation of our own members. The amount will not

exceed the outlay on funeral solemnities annually expended by it. Such meetings tend to bring about amicable relations among the living, and to promote the interest in and distribution of knowledge. It might be good politics if the Canadian Boundary and Venezuelan questions should be still on hand in 1897.

RECENT LITERATURE.

Petrology for Students: An Introduction to the Study of Rocks under the Microscope, by Alfred Harker, University Press, Cambridge. MacMillan & Co., New York, 1895. Pp. vi and 306; figs. 75; price $2.00.

This volume of the Cambridge Natural Science Manuals will be heartily welcomed by teachers and students of geology in all Englishspeaking countries. It presupposes a knowledge of the microscopical features of minerals, and consequently deals only with rocks. These the author divides into Plutonic, Intrusive, Volcanic and Sedimentary rocks. Under each head the general characteristics distinguishing each of the several rock classes are briefly mentioned, and descriptions. of the different rock types embraced in each group are given. First come descriptions of the constituents of each rock, then follows a statement of its pecularities of structure. The principal varieties are next mentioned, and abnormal, structural and chemical forms are briefly described. The book concludes with chapters on thermal and dynamic metamorphism and one on the crystalline schists.

Of course, the treatment of the different subjects discussed is necessarily very brief, nevertheless it is full enough in most cases to give the student beginning petrography a very good view of the field. A specially important feature of the work is the large list of references to articles written in English. With this book at hand, students will no longer be required to wait until they have mastered German before beginning the study as heretofore been the case. While by no means exhaustive, the present volume will serve as an excellent introduction to the larger French and German treatises, and will, at the same time, be a good reference book for geologists who do not desire to make a specialty of microscopic lithology. W. S. B.

Crystallography, a Treatise on the Morphology of Crystals, by N. Story-Maskelyne, Oxford, Clarendon Press, 1895.

New