ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 181 



age. It appears to be definitely established that true interstitial cells 

 are always present in the ovary ; it is in regard to the testes that the 

 discrepancy exists between observers. The anthors find interstitial cells 

 in the testes of just-hatched chicks. But they may be, and usually are, 

 totally absent from the testes of males over six months of age and of 

 full sexual maturity, both in respect of primary and secondary characters. 

 It is difficult to suppose that they have any causal influence upon 

 secondary sex-characters. The true interstitial cells are not merely 

 homologous, but indeed structurally identical in the male (when present) 

 and in the female. 



Effects of Pituitary Body and Corpus Luteum on Chicks.* — 

 Raymond Pearl finds that feeding with corpus luteum and the anterior 

 lobe of the pituitary body retarded the growth. The retardation was 

 greater with corpus luteum. After forty-three days the birds fed with 

 pituitary substance weighed on the average -4 '01 p.c. less than the 

 control birds, those fed on corpus luteum substance 9 '31 p.c. less. 

 There was no apparent difference in the time of attaining sexual 

 maturity. There is no evidence that the administration of pituitary 

 substance hastened in any way the initial activation of the pullet ovary. 

 The corpus luteum treatment does not produce any physiological dis- 

 turbance. 



Hermaphrodite Dogfish.f— Ruth C. Bamber describes a case of 

 hermaphroditism in ScyUium cankiila, which showed two testes, and on 

 the dorsal anterior of the right one a small mass of ova. Except for the 

 absence of sperm-sacs, the animal had the complete genital systems 

 of both male and female. Externally it was a typical male. 



Removal of Pronephros of Amphibian Embryo.| — Ruth B. Rowland 

 removed the pronephros from both sides of AmhJystoma larvse. This 

 induced oedema and death. The presence of one sufficed to keep the 

 embryo in health. Excision of one wfis followed by an increase in the 

 size of the other, and in the diameter of the segmental duct. Removal 

 of one pronephros has no essential effect on the development of the 

 pronephric glomerulus of that side, but the segmental duct appears 

 in varying stages of atrophy. Anterior and posterior nephrostomes 

 may regenerate from the coelomic epithelium. Early developmental 

 stages of the mesonephros are normal after the excision of one hind- 

 kidney. 



Inheritance in Fantail Pigeons. § — T. H. Morgan crossed fantails 

 with 29, 30 and 32 tail feathers and ordinary homers with 12. In the 

 Fj generation the range of variation was 12 to 20, with the highest 

 frequency in the 14-feather class. " Evidently one or more of the 

 factors of the fantail act as partial dominants, producing tails that have 



* Proc. Nat. Acad. Sci. U.S.A., ii. (1916) pp. 50-53. 



t Proc. Zool. Soc, 1917, pp. 217-9 (2 pis.), 



X Proc. Nat. Acad. Sci. U.S.A., ii. (1916) pp. 231-i (1 fig.). 



§ Amer. Nat., lii. (1918) pp. 5-27 (14 figs.). 



