254 WILBUR WILLIS SWINGLE 
It is generally only in the amphitene and diplotene that the 
line of fusion of the conjugants is visible in the bullfrog larvae. 
In this connection it is interesting to note that Janssens ('05), 
in his study of Batracoseps, was unable to detect any indication 
of a paired condition. Wilson ('12), in his examination of the 
same animal, agrees with Janssens that the pachytene threads 
appear as if single. 
The pachytene period in anurans larvae is in all respects like 
that described for urodeles. In many cases the free ends of the 
thickened threads are applied close to the nuclear membrane at the 
proximal pole, the broad loops extending distally, thus giving rise 
to the pachytene bouquet. Janssens ('05) divided the pachytene 
in Batracoseps into two distinct periods: the 'bouquet oriente,' 
corresponding to the condition just described, and the 'bouquet 
transverse,' in which the nuclear contents have apparently rotated 
in relation to the sphere, so that the bouquet instead of being 
oriented toward the centrosome and sphere is turned at right 
angles to it. The writer is unable to say definitely whether the 
period of the transverse bouquet does or does not represent a 
well-marked stage in the maturation cycle of Rana catesbeiana. 
Very probably this stage is more marked in urodeles than in 
anura. 
In Bufo, King ('07) derives the pachytene spireme from the 
irregular, deeply staining, confused chromatin mass of the synize- 
sis period. Her figure 25, plate 1, is a clear expression of her idea 
regarding the derivation of the pachytene threads. According to 
her account, it is a continuous spireme, does not show any evi- 
dence of longitudinal splitting, and later in the course of develop- 
ment segments transversely into the reduced (haploid) number of 
chromosomes. If this account of conditions in Bufo is correct, 
then this anuran differs from other amphibians, both caudate and 
tailess, in respect to formation of the pachytene spireme and the 
tetrads. The writer is under the impression that the difference 
between Bufo and other forms rests upon a misinterpretation of 
synizesis and synapsis, and if reexamined Bufo will very likely 
be found to conform to the amphibian type of maturation cycle. 
