NEW TYPES OF CHROMOSOME DISTRIBUTION. 139 



them easily recognizable in the male and female cells, help to 

 confirm the above statement. Six are present in the female and 

 only four in the male, and this is what we would expect, since 

 one class of spermatozoa has three small chromosomes and other 

 one. 



The differential chromosomes have not been followed through- 

 out the entire growth period. Fig. 6, M , shows the appearance 

 of the nucleus during the greater part of this period. A large 

 pale plasmosome is present in which are embedded the four 

 differential chromosomes. The condition is almost exactly 

 analogous to that found in Prionidus. In the prophase of the 

 first division, the plasmosome disappears and the four differential 

 chromosomes stand out clearly as condensed deeply staining 

 bodies while the other chromosomes are condensing. 



Gelastocoris (Galgulus) oculatus Fabr. 



In a preliminary note ('08), I described a new type of sexual 

 difference in the chromosome groups of Gelastocoris oculatus. 

 At that time my material was limited and some of my conclusions 

 were supported by only a few observations. Since then I have 

 obtained new material and am now in a position to reaffirm all 

 that was stated in the former paper. My figures of the first 

 division showed among the chromosomes one or two minute dark 

 bodies resembling yolk granules. As stated at that time, a doubt 

 might be raised as to whether these bodies were chromosomes. 

 However, my opinion as stated, was supported by the facts that 

 the number of chromosomes in the prophase of the first division 

 before the nuclear wall broke down, was always 20, and that the 

 metaphase plate of the second division invariably showed 20 

 chromosomes. In my new material, I have found several meta- 

 phase plates which show 20 chromosomes without any granules 

 whatever (Fig. 7, A' and L). As the spermatogonial number is 

 35, 15 of the 20 must be bivalent and five univalent. There is 

 no definite arrangement of the chromosomes in this division, but 

 sometimes 15 are in a more or less irregular ring with the other 

 five in the center, as is shown in Fig. 7, L. Whether these five 

 are the same ones which form the pentad group in the second 



