GERM CELLS OF ANURANS 261 
The obvious cause of degeneration of the spermatocytes of first- 
season larvae is to be found in the abnormal behavior of the 
centrosomes. Very early in the work it was observed that multi- 
polar mitotic figures were exceedingly frequent, and, indeed, 
these came to be regarded as the rule rather than the exception 
in the maturation cycle of first-year tadpoles. Triasters and 
tetrasters with striking and bizarre chromosomal arrangement 
proved so common that attention was focused upon the centro- 
some as the primary seat of degenerative processes. It may be 
added here that these aberrant polyasters are very favorable 
objects of study in Rana catesbeiana larvae because of their size 
and number and should prove of interest to anyone concerned 
with cellular mechanics. 
Fragmentation of the centrosome of first-year larval spermatocytes 
A study of the centrosome of the first-season spermatocytes 
proved very fruitful in several respects: 1) it gave the clue to 
correct interpretation of the anomalous behavior, i.e., the failure 
to divide of the spermatocytes; 2) the results of such study 
explained on sound mechanical grounds the presence of the poly- 
asters; 3) it led to the discovery of certain giant spermatid-like 
structures. 
In most, if not all, of the first-season larval spermatocytes, 
the centrosome behaves abnormally, rarely does it pass through 
the normal cycle and give rise to a typical bipolar spindle. The 
usual thing is fragmentation of one or both halves of the divided 
centrosome; figures 18, 21, 79 show such fragmentation. There 
may be a central granule, surrounded by four or five others, all 
connected to one another by very delicate filaments. Each of 
these granules may or may not form a tiny aster in the cj^toplasm. 
In other cells a typical spindle may be formed at one pole with 
numerous smaller spindles at the other pole. There are several 
variations of this type (figs. 18, ^1, 79). 
Perhaps the most peculiar condition noted in the centrosomal 
behavior of the spermatocytes was the tendency to form axial 
filaments or tails. It required much searching to find anything 
