(Caption of Figure 3 , continued) 



11. Embryo after 96 hours of incubation; the vertebrae are 

 visible (g) ; rudiments of extremities (r) and heart (c) . 



12. Half of vertebra of embryo of 34 hours; c — substance 

 surrounding the column; r — rudiment of the extremity. 



13. Posterior part of the vertebra of the embryo of the 

 fifth day; g — vertebra; r — extremity; b — condensation 

 of substance, giving the origin of the rectum between 

 extremities and the tail, and also kidney (d) ; 



e — remnants of urinary sac and membrane of the umbilical 

 vessels . 



14. Spirit preparation of chicken embryo, slightly magnified; 

 — occiput; S — forehead; r — beak; v — vertebra; 



e — extremities; a — abdomen. 



1 5 . Pelvis and lower part of the abdomen of the embryo 

 represented in Figure 14; covers of the abdomen; b — red 

 fluid, the same as under letter b in Figure 13; d — place 

 of removed rectum; f — place where intestine passes in 

 the still unformed substance e; c — substance giving the 

 origin of the ureter. 



16. Kidneys (b) and rectum (e) with caecum of embryo somewhat 

 later than in Figure 14; c — ureters; d — the lower part 



of the rectum. 



17. Nearly formed kidneys (b) ; c — ureters; d — rectum. 



60 



