THE NERVOUS SYSTEM. 



487 



^ 



/..>■ 





r s* * 



^j\ _ , ..... j r - : ^. 





iiile 



mle 



Fig. 419. 



,r ; g mli 



/ " - ■ \ J! 



Fig. 420. 



Fig. 417. — From the neural tube of an embryo rabbit shortly before the closure of the tube ; g, Germi- 

 nal or dividing cell; m, peripheral zone, position of the later marginal layer. His. 



Fig. 418. — Pig of 5 mm., unflexed. Just after closure of the neural tube. Segment of a vertical 

 section of the lateral wall of the tube, g, Germinal cells; m, beginning of marginal layer; 

 mli, internal limiting membrane; ■/, radial columns of protoplasm. The resting nuclei lie in 

 the inner or nuclear layer. Hardesty. 



