ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 563 



breaks through and remains open for a considerable time ; the first 

 rudiment of the gills consists of paired protrusions, as in Polypterus ; 

 there are rudiments of spiracular and opercular gills; as in Selachians, 

 each visceral cleft has a thymus rudiment, though only from the second 

 to the fifth (as Bryce has shown in Lepidosireri) are the primordia 

 separated off as independent bodies. Another general conclusion is that 

 the gills in all Amphibians are purely ectodermic structures. 



Influence of Lecithin on Determination of Sex.* — C. Basile has 

 experimented with rabbits, into which he injected lecithin. There seems 

 to be an increase in reproductivity, the general nutritive conditions being 

 improved by the lecithin injections. But the lecithin treatment seems 

 also to increase the mortality of the young germs and the frequency of 

 abortive development. The treatment does not seem to increase the 

 number of female offspring. 



Interstitial Cells in the Ovary of Mammals. f — P. Aime pub- 

 lishes an account of his investigations on the interstitial cells of the 

 ovary of some Mammals. He finds that the interstitial tissue is a 

 very inconstant structure, aud that it is, therefore, not an essential 

 organ comparable in importance to the corpus luteum. The interstitial 

 cells arise from the cells of the embryonic connective-tissue. They 

 develop either at the expense of the embryonic mesenchyme cells, 

 or at that of the Graafian follicles. In the majority of Mammals 

 they are absent altogether. Where they occur, their evolution usually 

 begins after birth, but in the horse they are characteristic of the 

 embryonic period. Their glandular function is evident. They do not 

 divide, they are closely connected with the capillaries, and they present 

 all the cytological characters which indicate glandular activity. Their 

 resemblance to the interstitial cells of the testis is purely morphological. 

 In the horse young interstitial cells and xanthochromous interstitial 

 cells are found in the foetal ovary as well as in the testes, but there are 

 no interstitial cells in the ovary of the adult. The only internal secreting 

 -land in the ovary of the adult horse is the corpus luteum. The 

 hypothesis that the interstitial cells have a trophic role in relation to 

 the sexual cells has some probability if it be based on the time of their 

 appearance, which precedes that of the Graafian follicles. But this role 

 is difficult to explain in view of the fact that a great many animals in 

 which the ovary is absolutely crowded with ovocytes have no interstitial 

 cells at any period of their lives. The author admits that the function 

 of the interstitial cells is still unknown, but he suggests, with regard to 

 the horse, the theory that there is an equilibrium between their internal 

 secretion in the foetus, and the internal secretion of the maternal corpora 

 lutea during the first half of gestation. 



Compensatory Hypertrophy in the Ovary 4 — E. S. Carmichael and 

 F. H. A. Marshall have experimented with rabbits, testing Bond's con- 



* Atti R. Accad. Lincei Roma, xvii. (1908) pp. 643- 52. 



t Arch. Zool. Exper. et Gen., vii. (1907) pp. 95-143 (3 pis.), 



X Journ. of Physiol., xxxvi. (1908) pp. 431-4. 



2 P 2 



