Plate V 





A F, prophases of heterotype division of spermatocytes of Guinea-pig, after 

 MOORE and WALKER. A, spireme (leptonema), B, synizesis (contraction 

 phase), C, zygonema, D, pachynema, E, resolution of contraction phase. 

 , appearance of definite double chromosomes. 



G, H, I, heterotype division in spermatocytes of the Grasshopper Stenobothrns, 

 after DAVIS. G, H, Metaphase, 7, Anaphase. 



