The nuclcar components of the sex cells of four species of cockroaches. 501 
The results of this study lead the writer to the following inter- 
pretations of the behavior of the ordiuary chromosomes; Parasynapsis 
of the chromosomes takes place in the synizesis or looped condition 
ot the chromosomes of the primary spermatocyte. There is an 
apparent fusion of the conjugants which renders the later history 
somewhat uncertain; but at any rate, each of the spermatocyte mitoses 
involves a longitudinal division of the chromosomes, with the ex- 
ception of the odd chromosome which goes to one pole undivided in 
the primary spermatocyte, but divides in the second. The writer is 
unable to determine whether any reduction division is present or, if 
there be one, which division may be characterized as such. 
We shall now briefly consider such points in the development 
of the sex cells of the other species as are of especial interest. 
Leucophaea maderiae Brun, and Redtenb. 
1. The spermatogonial and oögonial chromosome numbers. 
Unlike the spermatogonial chromosomes of Periplcmeta, those of 
Leucophcea have the form of "V’s” or bent rods (fig. 55). The 
ovarian chromosomes are of the same shape (fig. 56). The counts 
were much less satisfactory than in the case of Periplaneta although 
the chromosomes and the whole nucleus are larger and there is a 
smaller number of chromosomes in Leucophcea than in Periplaneta. 
In three cases, where the chromosomes were sufficientlv separated to 
be counted with accuracy, the spermatogonial number of twenty-three 
was determined (fig. 55). Two follicle cells of the ovary and one 
or two oögonia showed twenty-four chromosomes (fig. 56). There is 
considerable ditference in size among the chromosomes of both series, 
but it has not been possible to compose them in pairs and thereby 
discover the odd chromosome. 
^ 2. The synaptie period. 
The writer has been able to recognize the same thickening in 
the chromatin threads of the growth period in Leucophcea as was 
done in Periplaneta (figs. 57, 58 and 59). At first the threads are 
clearly undivided longitudinally (fig. 57), being very delicate Strands 
of chromatin running through the cell promiscuously. No polarization 
seems to occur in this species, but later (fig. 58), some of the threads 
become decidedly thicker and are longitudinally doubled, while others 
