268 WILBUR WILLIS SWINGLE 
spermatocytes give rise to normal spermatids and some sperma- 
tozoa, and the writer has nothing to add to this phase of the sub- 
ject that has not been described many times before in papers 
concerned with the spermatogenesis of other amphibians. 
Unquestionaly, these larval sperm cells are functional, because 
morphologically they are indistinguishable from spermatozoa of 
adult frogs (figs. 118 to 131). 
DISCUSSION OF OBSERVATIONS 
1. Amitosis in anurans 
It has frequently been stated by earlier investigators working 
with amphibian material that amitosis occurs quite commonly in 
the testis cells of urodeles and anurans. Several writers have even 
asserted that at certain seasons of the year amitosis is the sole 
method of division (La Valete St. George, Meves, Benda and 
McGregor) . It has even been seriously stated that the primary 
spermatogonia not only divide amitotically, but the results of 
such direct division become functional spermatozoa. Meves and 
Benda state that amitosis occurs by means of the constrictive 
force of a ring-shaped centrosome in Salamandra. McGregor 
states that the nucleus is divided by a cleft into two approxi- 
mately equal parts. Oddly enough, in view of these positive 
statements, the writer has never observed anything in primary 
or secondary spermatogonia or in follicle or stroma cells that is 
comparable in any way to amitosis. The polymorphic nuclei of 
the spermatogonia do somewhat superficially seem to be con- 
structed into two halves at times, and the constriction may be 
deep enough to give (fig. 1) the appearance of separate nuclei 
in the same cell. Careful study reveals connecting portions lying 
at deeper levels. It is evident from descriptions of amitosis in 
amphibians that polymorphism of the nucleus has been mistaken 
for direct division. The writer takes the position, perhaps ex- 
treme, that in the spermatogenesis of anura, amitosis does not 
normally occur, and if it ever occurs in these forms, it is an 
extremely rare and aberrant condition, save in senescent cells 
such as those of Bidder's organ, and even in this degenerate struc- 
ture direct division is uncommon. 
