unite sexually as I was careful to observe that the stylets of the male were actually inserted into the annulus of the female. Whether a spermatophore can be transferred under such circumstances is of course still a question.

The observations described in this paper would lead to the conclusion that the crawfishes have little or no power of sex discrimination. The male "tries "every crawfish which he meets and the instinct of the female is to remain passive under such treatment while another male will attempt to escape. The sexes come together as the result of random movements or in the course of the daily travelling about in search of food. Holmes reached similar conclusions as a result of his observations on amphipods. Male amphipods, however, would not attempt to copulate with a dead female and in this respect their powers of discrimination apparently excel those of the crawfish.

Holmes, S. J.," Sex Recognition among Amphipods," Biol. Bull., Vol. 5, 1903, No. 5, pp. 288-292.

SHORTER ARTICLES AND CORRESPONDENCE

DEGENERATION ACCOMPANYING INBREEDING

It seems now generally conceded that inbreeding per se is not injurious but that when a similar defect in the germ plasm comes from both sides of the family the children do not rise in respect to this character above the parental level. The effect of close inbreeding in small isolated communities is, at any rate, always interesting, and affords an excuse for the following note, based on facts gleaned from a letter sent me by Rev. H. East, a missionary whose headquarters are at Haka, Chin Hills, Burmah. Rau Vau village has been isolated for about seven generations. It contains about sixty houses and possibly two hundred inhabitants. Of these ten are idiots, many are dwarfs and some hydrocephalic. A number of cases of syndactylism and brachydactyly occur. Mr. East was not able, offhand, to state how these peculiarities are inherited, but it is to be hoped that he will be able to report on this subject later. Certainly, heredity in such a community deserves careful attention.

C. B. DAVENPORT.

A NOTE OF THE PRAIRIE-DOG OWL WHICH RESEMBLES THE RATTLESNAKE'S RATTLE

IN looking over an earlier number of the AMERICAN NATURALIST1 I find a note under this head by F. B. Loomis in which he describes a note of the adult burrowing owl which so closely resembled the rattle of a rattlesnake that not only the members of his party, but their horses as well, were deceived.

. . . it alighted and began a third rattle; and this time all saw its stretched neck, bulging eyes, open beak and vibrating tongue. The whole appearance of the bird indicated assurance that it would thus frighten off any enemy; and it certainly deceived the four plain-bred horses, as well as the men, all of whom had for weeks been familiar with rattlesnakes, and two of them for years.

This reminds me that about sixteen years ago I made some observations on the same subject. It is particularly interesting 1AM. NAT., Vol. XLI, pp. 725–726, 1907.

to me to note that the horses were invariably frightened by the "rattle," for in thinking of my own experience I have often considered that perhaps my observations were somewhat prejudiced that rattlesnakes are so popularly supposed to occupy the holes with the owls. The observations which Loomis records here were for an adult bird, while mine were upon the young.

A burrow was dug out and a nest of eight young secured. When taken from the burrow, and with great frequency, these young birds-still in the downy condition-made this sound. As I remember it, this occurred every time they were disturbed. These birds were taken in Cheyenne or Rawlins County, Kansas, while Loomis's observations were made in Wyoming. Loomis seems to regard the note as peculiar to the one individual he observed, for he writes:

If it succeeds in teaching this trick to its young, a protective habit of great value will be formed.

Whether the prairie-dog owl generally has this note I am quite unprepared to say, but my observations in northwestern Kansas indicate that it is not an individual peculiarity. It is so easy to attribute adaptive significance to characters that our attitude toward such suggestions should always be very critical; whether the note described is ever of any service to the bird would be a difficult problem for a field ornithologist. It would be interesting to know whether notes of this kind are peculiar to the prairiedog owl, or whether they are also heard in species which have no possible association with the rattlesnake. Some one familiar with birds in the field could probably answer this question.

J. ARTHUR HARRIS.

NOTES AND LITERATURE

THE CAUSATION OF SEX1

THIS book is the work of a general practitioner of medicine. For twenty years he has collected clinical facts and materials. upon which he now claims to have built up a new theory of sex. The theory has been put to the test in forecasting the sex of the unborn child and proved adequate in 97 per cent. of cases. The cause of sex being known in man, the determination of sex is readily accomplished. A summary disposition of Schenk's oncefamous superior-vigor-theory is made by simply citing the clinical fact of the occasional simultaneous birth of both a boy and a girl.

The theory dissociates absolutely the male parent from any influence in sex causation-thus differing from several otherwise closely similar hypotheses. It is simply that "sex depends upon which ovary supplies the ovum fertilized." The clinical materials employed in proof are: (1) Sexually differing families; (2) extra-uterine pregnancy; (3) pregnancy in double uteri; (4) multiple pregnancy; (5) migration of ovum (internal and external; (6) preponderance of male over female births. Furthermore, the author denies validity to all arguments, respecting sex in man, from analogy with invertebrates or even lower vertebrates, believing "women not analogous to any living thing.

Respecting the anatomy and physiology of the female generative organs the following facts are noted and employed in the construction of the theory: (1) Lower position in pelvis of right ovary and internal opening of right oviduct; (2) larger caliber of right oviduct; (3) larger size of right ovary; (4) occasional presence of two ova in a Graafian follicle; (5) recorded cases of double nuclei in the mammalian egg; (6) corpus luteum as indicator of ovary from which the impregnated ovum came; (7) dependence on common cause, consequently close coincidence, of ovulation and menstruation (proof: scars of corpora lutea correspond to the number of menstrual periods experienced). The The Causation of Sex," by E. Rumley Dawson, London, H. K. Lewis, 1909, pp. 190, 21 illustrations.

foregoing statements are supported mainly by quotations from various recognized authorities.

Chapters 3 and 5, dealing with the Formation of the Ova and Fertilization respectively, are vulnerable at various points to the criticisms of gratuitous assumption, specious reasoning and flagrant disregard of recent biological advance, more particularly respecting the questions of heredity and sex. Absolutely no notice is taken of the work of Bateson, Davenport and Castle on Mendelian inheritance, nor of the cytological and experimental results concerning the determination of sex respectively of Wilson and Correns. But however scant the appreciation of the bearing of results from non-human materials on the general problem, and however radical the ideas here expressed, the theory as such remains essentially unaffected.

In chapter 3 it is urged that "Each ovum has its own definite and unalterable sex, being either male or female according to the ovary from which it is derived." Though microscopic evidence of such difference is not yet forthcoming it is asserted to obtain "just as between the eggs of two different women." "Similarly the ovum of a negress is indistinguishable by our present appliances from the ovum of a blonde, yet we know full well that if fertilized one produces a black child while the other gives rise to a white one" (p. 29). Assuming, as this line of reasoning does, that there is identity (or at least close similarity) between the process of sex-inheritance and color-inheritance, both would seem to be due, in a large measure, to the influence of the male. For the ovum of a negress fertilized by the spermatozoon of a blonde male might give rise to a black child, but it would more likely be a mulatto, perhaps almost indistinguishable from a blonde-similarly sex may be influenced or determined by the spermatozoon.

Identity in the mechanism of heredity, whether it concern sex, color or other unit characters, is widely accepted; but Dr. Dawson seems to posit such identity or the absence of it depending upon the conclusion he desires to reach. Above he posits identity; but he reasons incorrectly in an attempt to reach a desired conclusion.

In a later chapter (chapter 5), starting with the assumption that the "provision in the human ovum of multiple avenues of entrance (the radiating pores of the zona pellucida) looks as though multiple spermatozoa are required to enter thereby in order to fertilize the human ovum," he argues that the "differ