14 PAULINE H. DEDERER 
the chromosomes of the oogonia, since the split appears de novo, 
and also since there is no direct evidence that the chromatin 
threads have conjugated in synapsis. Unfortunately, therefore, 
P. cynthia cannot be added to the list of forms in which either 
parasynapsis or telosynapsis has been observed. The impres- 
sion gained from a study of the material is that reduction is 
accomplished by a simple segmentation of a continuous spireme 
into the haploid number of threads. 
Following upon figure 48, a progressive shortening of the 
segments occurs, the chromosomes often appearing extremely 
ragged. In a few cases, the halves show a divergence at one 
point as if beginning to separate (fig. 49). Very rarely the threads 
open in the middle while remaining united at the ends, thus 
forming a ring, but these forms are probably accidental and due 
to the fact that the chromosomes are soon to disintegrate. The 
later condition of this stage is shown in.figure 50. The threads 
have by this time assumed a rod-like appearanee. The length- 
wise split is still apparent, but the chromosomes are extremely 
ragged and irregular in outline. Thirteen rods are present. 
At about this stage in Abraxas, Doncaster (’12) found the egg 
cells differentiated. In P. cynthia, as will be shown, the period 
is somewhat earlier. . ; 
Stage h (figs. 37 d and 51). In figure 51 almost all of the rods 
have shortened to bipartite chromosomes, the halves being 
rather widely separated from each other. Frequently a con- 
striction in each half gives a tetrad form to the chromosome. 
In this figure, two are still rod-like, as in the preceding stage. 
The large plasmosome is frequently vacuolated. In figure 52, 
a later condition, the chromosomes are more irregular and stain 
less deeply. A few of the tetrads are broken into four separate 
flocculent pieces; others into irregular fragments. Some chromo- 
somes remain bipartite as before. Within the cytoplasm a 
dark rounded mass indicates the end of the strand or tube which 
connects this cell with others. 
With further growth of the cell, the nucleus increases in size, 
and the chromatin fragments multiply considerably. Giardina 
(01), Debaisieux (09) and Giinthert (10) have figured in the 
