ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 451 



It would thus appear that the behaviour of spermatozoa towards 

 " agglutin " is identical with their behaviour towards a trivalent kat-ion. 

 The nature of the electric charges upon the surface of the gametes may 

 play an important role in the behaviour of these cells. 



In an interesting note the question is raised whether the limit of 

 migration of Luidia is fixed by the alkalinity of the sea-water. 



Spermatogenesis in Domestic Chicken.* — Alice M. Boring and 

 Raymond Pearl discuss the sio-nificance of the odd chromosome in the 

 spermatogenesis. In the Black Langshan Breed it has been reported by 

 Guyer that an X-chromosome goes into one-half of the secondary 

 spermatocytes, thus giving rise to two kinds of spermatozoa, half with 

 X and half without. If this X-chromosome is assumed to be a sex 

 chromosome, as in so many forms, the male bird, according to Guyer's 

 account, must be heterozygous in regard to sex. 



In the Barred Plymouth Rock breed there is no convincing evi- 

 dence of the existence of a sex chromosome. In 11 • 82 p.c. of first 

 spermatocytes and 3 * 06 p.c. of second spermatocytes, there is a piece 

 of chromatin similar to that called an X-chromosome by Guyer in 

 Langshan males. This is not to be regarded as an X-chromosome in 

 Barred Plymouth Rocks, for it is present in spermatocytes of both 

 orders ; and it varies in shape, size, and number. In no single cell is it 

 of such a shape or size, or in such a position, that it could not readily 

 be interpreted as anything else than an X-chromosome. A statistical 

 study of Barred Plymouth Rock cells in comparison with those of the 

 Hemipterous insect Philsenus spumarius shows that it is present in too 

 few primary spermatocytes and in too many secondary spermatocytes, or 

 vice versa. It is still present in too few cells, if it should be interpreted 

 as one of those rare cases where the odd chromosome divides in either 

 the first or the second spermatocyte division. 



Interstitial Cells in Chicken's Testes.f — T. B. Reeves calls atten- 

 tion to Miss Boring's conclusion that there are no interstitial cells 

 present at any time in the testes of chicken from one day to twelve 

 months old, and to the work of J. des Cilleuls who found interstitial 

 cells from the thirteenth day onwards. Reeves examined the testes 

 from cocks five and a half, nine, and eighteen months old, and found 

 interstitial cells in all the stages examined. 



Size Dimorphism in Spermatozoa from Single Testes.! — Charles 

 Zeleny and E. C. Faust have made a large number of measurements of 

 the sperm-heads in various insects, and also in a frog, a Chelonian, and 

 three mammals. The plotted curves of variation in size indicate strongly 

 the existence of size dimorphism in most of the species studied. Thirty- 

 three separate determinations were made, with an average of about 523 

 measurements for each determination, and a total of 17,252 for the 

 whole. 



In nearly all cases there were two high points or modes in the 



* Journ. Exper. ZooL, xvi. (1914) pp. 53-82 (G pis.). 



t Anat. Record, ix. (1915) pp. 383-6 (3 figs.). 



% Journ. Exper. ZooL, xviii. (1915) pp. 187-240 (43 figs.). 



