372 The Spermatogenesis of Bufo Lentiginosus 
various times during the summer months and also in the testes of young 
toads, so that in Bufo it is impossible that they can be “ anomalies.” 
The results of my work on Bufo, therefore, are in full accord with - 
those obtained by vom Rath on Rana and Salamandra which have been 
ignored or severely criticised by other investigators of amphibian 
spermatogenesis. 
The evidence brought forward by investigators who have studied the 
maturation phenomena in the eggs of amphibians has been overwhelm- 
ingly in favor of the occurrence of a double longitudinal division of 
the chromosomes previous to the extrusion of the polar bodies. Carnoy 
and Lebrun (9), and Lebrun (30, 31) have published a series of memoirs 
dealing with the formation of the polar bodies in the eggs of various 
amphibians, and they have emphatically denied the occurrence of a re- 
duction division in the forms that they have studied. In my earlier 
study of the maturation of the egg of Bufo lentiginosus (King, 26) 
I was inclined to believe that both of the maturation divisions are longi- 
tudinal; but a later examination of a much more complete series of 
preparations of the first polar spindle (King (27)) led me to suggest 
the probability that the first maturation division is a reduction division. 
In light of the present study of the spermatogenesis of Bufo, and of 
investigations, not yet completed, on the ovogenesis of this amphibian, 
I am convinced that in the ovocytes as well as in the spermatocytes the 
first maturation division is a reduction division and that the second 
division only is longitudinal. 
Although all investigators agree that the head of the mature sperm- 
atozoén is derived from the nucleus of the spermatid, there is no such 
unanimity of opinion regarding the origin of the other parts of the 
spermatozoon. 
The middle-piece of the amphibian spermatozodn has been described 
as arising from the chromatin of the nucleus (Biihler, Flemming (16) ) 
from the inner centrosome (Meyves) ; from a part of the idiozome (Mc- 
Gregor) and from a nebenkorper (Hermann (20)). In the very young 
spermatids of Bufo the middle-piece anlage is frequently found some 
distance from the nucleus (Fig. 60), and there is therefore very little 
probability that it is a nuclear product. The appearance of the anlage 
of the middle-piece before the centrosome has divided precludes the 
possibility that it is derived from the inner centrosome. If, therefore, 
this structure is other than modified cytoplasm, it is very probably de- 
rived from the idiozome. As there is no structure in the spermatid at 
this time that at all resemble an idiozome, it must be that the entire 
