GERM CELLS OF ANURANS 257 
•univalent chromosomes united telosynaptically at the angle of the 
loop. According to this point of view, the space between the two 
arms of the loop is the space between two univalent chromo- 
somes, but does not represent the line of fusion of originally 
separated leptotene threads. This view, while erroneous (admit- 
ted to be so b}^ Montgomery himself, '12), leads to essentially the 
same end results as those stated by the writer. 
There are fourteen typical rings and crosses plainly of tetrad 
nature in the spermatocytes of the bullfrog larvae and in some 
cells a large rod-shaped body may appear (fig. 26 to 28). The 
rings are of large size as compared with similar chromosome 
stages of adult frog material and are practically identical with 
those of urodeles in regard to size and shape. In the larvae 
these rings can be grouped according to their size relations — one 
very large ring (fig, 18), five intermediate in size (fig. 20), and 
eight smaller ones (fig. 21), The size relations of these rings in 
various cells is apparently constant for the species in cells of the 
same size, and this is an important point, for there is a variation 
of chromosomal size in cells of different size. The amount of 
volume of cytoplasm has much to do with the size of the chromo- 
somes. Figures 29, 30, 31, and 32 bring out clearly this difference 
in chromosome size when two cells in identical stages but of dif- 
ferent size are compared. The thinness of the chromosome 
group in figure 78 is not entirely due to stretching on the spindle. 
The chromatin mass varies in proportion to cellular size, i.e., the 
larger the cell the larger the chromosomes, and vice versa. Conk- 
lin ('12) has clearly shown and discussed this point also in numer- 
ous other papers. The extremely large cells shown in plates 7 
to 14 have relatively large tetrads, conversely the smaller cells 
figured in plate 15 have much smaller tetrads. The photographs 
of plates 7 to 14 are of larval cells, those of plate 15 of the germ 
cells of animals at the time of metamorphosis. 
Ring tetrads in amphibia have been described by several previ- 
ous writers, so onlj^ a brief discussion is needed here. Following 
the separation save at the synaptic ends in the diplotene of the 
paired elements, and the appearance of the secondary split, the 
rings open in two planes at right angles to each other: 1) In the 
