PLATE 4 
EXPLANATION OF FIGURES 
Microphotographs on this plate made at magnification of 50 diameters. No 
reduction. 
33 Transverse section through male gonad shown in text figure 1, a. Note 
the very large secondary genital cavity surrounded by double layer of germ cells. 
Animal 40 to 50 mm. total length. Maturation of the germ cells begins in many 
instances in undifferentiated glands of this type. 
34 Cross-section through male gonad of first-year tadpole (text fig. 1, b). 
The large cavity is disappearing, owing to rapid proliferation of germ cells. The 
cavity is lined by non-sexual mesodermal cells which have migrated in from 
the mesonephros. Practically all the germ cells in this type of larvae gonad are 
maturating. Animal 70 to 95 mm. total length. 
35 Section through male gonad of second-year tadpole approaching meta- 
morphosis (text fig. 1, C). The cavity has disappeared. Note the testicular 
ampullae. The second sexual cycle occurs in this type of testis. Animals 120 
to 150 mm. total length. 
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