GERM CELLS IN THE ARTHROPODA 131 
generation. This rod is considered by Montgomery 
to be of cytoplasmic origin and is termed by him a 
“Sertoli cell determinant.” During the division 
Antepenultimate 
Spermatogonlum 
Penultimate 
Spermatogonia —— 
Loa, 
f \ oN 
Ultimate 
Spermatogonia 
ER SS ae + 
Germ Cells Proper 
-R 
Sertoli “ ae 
cell \ 
Fic. 42.— Diagram illustrating the differentiation of the Sertoli cell in 
man. (From Montgomery, 1911.) 
of the antepenultimate spermatogonia the rod passes 
undivided into one of the daughter cells; thus one- 
half of the penultimate spermatogonia possess a 
