FACTORS IN ONTOGENY 





i^iG. 145. — Cell fission in the salamander: ^.Resting nucleus slagp. centrtisome pnrtly 

 developed: B, skein stage, chromatin visilile as a convolute*! hand, the con t nwomrs 

 having separated; C. the nuclear mcmhrane having .hsappoared. an<l a frw of ihe 

 chromosomes lying free in the cytoplasm; D. central spindle rnmplete. the chr<»- 

 mosomes on splitting heing drawn to the spin.lle; E. metuphajsc; F, anaphuMr. tho 

 chromosomes being drawn to the poles, (.\fter Driiner.) 



