Piate LVIII 
B 
(a) Portion of a pachytene nucleus of C. Lachryma-Jobi var. typica 
(population Campus wild) showing the nucleus organizer chromosome. 
This population exhibits differentinl staining of eu- and heteropcynotic 
regions of the chromosomes which is evident in this cell. (b) A camera 
lucida drawing of the nucleolus organizing chromosome. 
