Figs. 4-6. From the same brain as Fig. 3 (2/2- to 3-day chick embryo, 200 r, 9 

 hours). Carnoy fixative; May-Griinwald and Giemsa stain. 



Fig. 4. The lumen is at the top of the figure. X 1100. 

 Fig. 5. The lumen is at the top of the figure. X 800. 

 Fig. 6. Enlargement of cell indicated in Fig. 5. X 3000. 



86 



