PLATE 15 
EXPLANATION OF FIGURES 
117 Primordial spermatogonium with large vesicular nucleus. This type of 
cell, in very small numbers, persists unchanged through the first-year maturation 
cycle of the larvae, and by repeated divisions probably contributes the cells of 
the second sexual cycle of the larvae. 
118 and 119 Small germ cells of second-year tadpoles preparing for the second 
sexual cycle. Compare these cells with figure 117. Both types of cell are found 
in the same gonad. The smaller elements appear to originate in part from 
transformed mesothelial cells (?). 
120 to 123 First spermatocyte prophases. Note the small size of the cells 
and tetrads. Compare with figures 112 or 114 or any cell on plates 7 to 13. 
124 to 128 First spermatocyte divisions oi second larval sexual cycle, or newly 
metamorphosed frogs. Note extremely small size of cells and tetrads. Compare 
with plates 7 to 13. Clearness of detail of the chromosomes has been sacrificed 
by overdevelopment to show the spindles and cell outlines. 
129 and 130 Spermatids of second sexual cycle. 
131 Spermatozoa of second larval sexual cycle. These are sometimes formed 
in large numbers in the larvae, but are more numerous shortly after metamor- 
phosis. 
330 
