Figure 333. — Thymus. Chick, 35 days after hatching. Composite drawing from 4 pLaces on same 



slide. 1,370 X. 



1 Rounded thymus reticular cell. A primordial cell. 



2 Slightly squashed reticular cell. 



3 Lymphoblast. 



4 Immature lymphocyte at transition to mature 

 lymphocyte. 



5 Immature lymphocyte, slightly more differentiated 

 than 4. 



G-9 Medium mature lymphocytes. 



10-12 Small mature lymphocytes. 



13-15 Smudged nuclei. 



16 Mature heterophil. 



17 Smudged heterophil. 



18 Mature basophil. 



172 



