DIFFERENTIATION OF NEUROBLASTS 



91 



10 



Figs. 1 and 2, and i to 10 were drawn after isolated, wholly undifferentiated, 

 neuroblasts from necturus had developed from 40 to 70 hours in the culture 

 medium described. Magnification about 400 diameters. One end of a fibre rep- 

 resented in fig. 8 grew beneath an opaque mass, and a portion of one represented 

 by fig. 10 grew beneath 9. 



Fig. 3 represents a mass of fibres growing from a small portion of the medullary 

 canal about 67 hours after being placed in the culture medium. 



For further explanations see text. 



