McAllister—Cytology and Embryology. 613 
no confusion exists in their minds as to the distinction be¬ 
tween them. 
It is to be noted that Farmer and Moore found the second 
contraction stage well marked in all the forms which they re¬ 
ported on,—in Lilium, in Osmunda, in Aneura, and in the 
ovogenesis of the cockroach. It may be of further significance 
in this connection that out of the 17 citations above of authors 
reporting the second contraction stage, 13 cases have been re¬ 
ported by investigators seeking to uphold the end to end pair¬ 
ing of parental chromosomes with the subsequent bending to 
form the heterotypic chromosomes. 
Fraser and Brooks (29) have reported a “first contraction 
stage’ 7 and “a second contraction stage or synapsis 77 in the re¬ 
duction divisions in the ascus of Humaria rutilans. Here the 
situation is complicated by the fact that according to Fraser and 
Brooks the nuclear fusion in the ascus is preceded by “the 
first contraction stage 77 in the nuclei which fuse, and immedi¬ 
ately follows the recovery from this contraction. The fusion 
takes place while the two nuclei are in the split spirem stage, 
and the second contraction takes place therefore after the fu¬ 
sion of the two nuclei. Just how these two spirems are to be¬ 
come associated to form the loops of the second contraction 
stage the authors do not show. 
That the second contraction figure has been observed by other 
investigators and has not been recognized by them seems clear 
from an examination of the figures of various authors repre¬ 
senting the later prophases of the reduction divisions. 
Strasburger (96) in his Figures 84 and 85 shows good second 
contraction figures for Tradescantia* virginica. He calls at¬ 
tention to this massing in the center of the nucleus but makes 
no reference to the work of Miss Sargent and others on this 
stage. Ernst (22) represents a good second contraction figure 
(Fig. 7) for Paris quadrifolia which he describes as a late 
stage in synapsis, but from the thickness of the spirem strands 
it seems clear that the stage of the uniformly distributed spirem 
has been overlooked and that his figure really represents second 
synapsis. Berghs (7) (Fig. 3) shows a similar figure for the 
