SEX-CORDS AND SPERMATOGONIA IN rilK'K 



397 



article (Swift, '15) this same arrangement was observed in the 

 oogonia of the chick and it is my beUef that any cell in the male 

 which has this character is a spennatogonium. Certainly all 

 the spermatogonia of much later periods possess this distinguish- 

 ing character. I believe, then, that spermatogonia foniiation 



p.c. 





m 



Fig. 4 Portion of a transverse section through the left testis of a 17 day 

 chick embryo. This section of a massive seminiferous cord contains peritoneal 

 cells and spermatogonia. All the spermatogonia contain the mitochondrial 

 crescent. At this age practically all the primordial germ-cells have given way 

 to the spermatogonia. 



