ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 241 



to the capsule at the time of operation. It seems that the cell-divisions 

 of the mother sperm-cells which provide the spermatozoa in the re- 

 generated testis do not take place in exactly the same order, or are not 

 exactly of the same kind, as those which form the sperm-cells before 

 the castration. The facts suggest that the stimulus may alter the 

 character of or the proportionate rate of cell-division : but further 

 enquiry is necessary. 



Influence of Rbntgen Rays on Ovaries.* — Manfred Fraenkel has 

 experimented with guinea-pigs. An animal was subjected to the rays 

 on the fourth day after birth. Its growth was retarded. It became 

 mature and had offspring which were undersized. Their offspring were 

 undersized also and were sterile. In the experiments several servings 

 and pregnancies were failures. A hair defect was produced by the 

 rays on the head of the first animal, and a similar defect appeared on 

 the same place in the next generation : and similar cases were observed. 

 All the animals showed an accumulation of fat. Cystic degeneration of 

 the ovaries was observed in the sterile forms. 



Development of Gonads in Chick.f — Jean Firket has made a 

 careful study of this problem. In the early primordium two formations 

 are to be distinguished, similar in aspect, but different in significance : 

 (a) the urogenital connexions or the rudiment of the rete ; and (b) the 

 genital strands or epithelial strands of the first proliferation. In the 

 chick the urogenital connexions appear first. They are seen in an embryo 

 of ninety-five hours, as a mass of compact tissue adjacent to sixteen 

 primary Wolffian glomeruli. These glomeruli form part of the middle 

 portion of the mesonephros. In the chick, the urogenital connexions 

 differentiate within the mesenchyme, which occupies the space between 

 the germinative epithelium and the Wolffian glomeruli. They are dis- 

 tinctly isolated from the former. Their relations with the glomeruli are 

 secondary. 



In Amniota the urogenital connexions appear early. They are 

 derived from the special portion of mesoblast which lies at the point 

 where the pedicel of the somite is continued into the lateral plate. They 

 are homologous with nephrostomial canaliculi. The differences in the 

 relations between the urogenital connexions and the Wolffian body in 

 Mammals and in Sauropsida are due to the fact that the urogenital con- 

 nexions form a phylogenetically stationary ensemble, which does not 

 share in the cranio-caudal shortening of the urinary apparatus and the 

 genital primordium. 



The epithelial portion of the supra-renal capsule is derived from a 

 special portion of the peritoneal epithelium. This portion forms a 

 longitudinal linear zone, marked in its cephalic part by a deep and con- 

 stant groove ; it corresponds to the narrow space which separates the 

 Malpighian glomeruli of the Wolffian body and the sub-cardinal vein. 

 A portion of the supra-renal capsule arises, inits caudal half, from cellular 

 buds detached from the mass of the urogenital connexions. 



'& v 



* Arch. Mikr. Anat.,lxxxiv. (1914) 2te Abt.. pp. 111-18 (1 pi. and 6 figs.), 

 t Arch. Biol., xxix. (1914) pp. 201-351 (5 pis.). 



