370 The Spermatogenesis of Bufo Lentiginosus 
The condensation stage in the primary spermatocytes of Bufo is much 
more marked than in any of the other amphibians that have so far been 
investigated, and it is evidently a stage of relatively long duration, judg- 
ing from the number of cases that are to be found in every section of 
the testis of adult toads killed during the summer months. The changes 
occurring in the chromatin during this time cannot, of course, be ascer- 
tained; but it is evident, from an examination of iron-hematoxylin 
preparations that have been considerably destained (Fig. 23), that the 
chromatin does not become a homogeneous mass. In light of the results 
obtained from the study of the maturation phenomena in the germ- 
cells of other forms in which there is no synizesis stage, or one much 
less marked than in Bufo, it would seem as if the final steps in the 
process of synapsis must take place at this time although I am very much 
inclined to believe that in Bufo this process may have had its beginning 
in the very young spermatocytes (Figs. 10, 11). 
Whatever the changes taking place during synizesis, the chromatin 
emerges from this stage in the form of a continuous, homogeneous 
spireme. Although I have examined hundreds of spermatocytes at the 
stages of Figs. 24-28, I have never found the slightest indication of a 
longitudinal splitting of the spireme at this time. Such a splitting is 
first evident at the stage of Figs. 31-33, and then only in cases in which 
ring-shaped chromosomes are being formed. 
If the chromosomes conjugated side by side during synapsis so that 
the opening in the ring-shaped chromosomes shown in Figs. 32, 33, 36, 
and 38 represents the space between two univalent chromosomes, as 
Montgomery has maintained, then the first maturation mitosis, which 
undoubtedly divides the tetrads formed from the rings in the same way 
that it does the dumbbell-shaped chromosomes, does not separate uni- 
valent chromosomes, but cuts each univalent chromosome in half and is, 
consequently, a reduction division. On the same assumption, the second 
division would be in the plane of the union of the univalent chromo- 
somes and would separate the two remaining parts of each chromosome, 
being also a reduction division. Thus if we consider that the rings in 
the spermatocytes of Bufo are formed of two chromosomes A and B, 
which have conjugated side by side in synapsis as shown in diagram I, 
the first maturation division through the line X would cut each chromo- 
some into two parts: A would be divided transversely into a’ and a’; 
while B would be divided into b’ and b”. The second division through 
the line Y would separate a’ from b’ in the one cell and a” from 6” in 
the other cell. Both of the divisions being reduction divisions, the in- 
