PLATE 2 
EXPLANATION OF FIGURES 
13 to 15 Three stages of the late prophase in the secondary spermatogonia.- 
16 to 20 Metaphases of secondary spermatogonia showing the X-chromosome 
(X) and the M-chromosomes (M, M’). Figures 16, 19 and 20 belong to the same 
individual, but to different cellular generations. 
21 Large chromosomes drawn from spermatogonia of the same individual to 
show variation in shape and size. The chromosomes represented in f have been 
diawn from one of the last spermatogonial mitoses. ; 
22 Metaphase of secondary spermatogonium seen in lateral view; the chromo- 
somes are split lengthwise. 
23 to 26 The large chromosomes as seen in the early anaphase of secondary 
spermatogonia, showing differences in the mode of attachment of the spindle 
fibers. 
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