136 CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTERA HETEROPTERA. 



285), while the other is a cell that lacks this hody. There are always two diplosomes 

 that can be recognized by their small size, but slightly larger than the smaller mono- 

 some. As in the preceding mitosis the smaller monosome always lies a little outside 

 of the plane of the other chromosomes, so in this second mitosis the larger one al\va3's 

 lies somewhat to one side of the equatorial plane {3Io. 1, Fig. 284 ) ; and by virtue of 

 this position it maybe recognized even upon pole view {Mo. 1, Fig. 285). Fig. 284 

 shows the 3 smallest elements, which we have found to Ije the smaller monosome (il/o. 

 2), and the two diplosomes [Di. 1, Dl. '2), all three of them showing a division con- 

 striction. This demonstrates that the smaller monosome divides, that the diplosomes 

 also do, and because the 12 autosomes are equally constricted they too must divide. 

 But the larger monosome {Mo. 1, Fig. 284) lies nearer one sjjindle pole than the other, 

 is never constricted, and in the anaphases (Fig. 287) passes without dividing into one 

 of the spermatids. 



Accordingly there are in this complicated case : 12 autosomes that divide in both 

 mitoses, 2 diplosomes that do likewise (therefore are probably also bivalent), a smaller 

 monosome that does not divide in the first but does divide in the second mitosis, and 

 a larger monosome that divides in the first but not in the second mitosis. Therefore, 

 each spermatid receives 12 autosomes and 2 diplosomes, while onl}' half of tliem re- 

 ceive the larger, and only half of them the smaller diplosome ; whether any spermatid 

 ever receives both monosomes, or whether any one ever lacks both monosomes, I 

 could not decide, because the chromosomes are closely crowded in the spermatids. 



From the relations of the chromosomes in the spermatocytes the elements in the 

 spermatogonium should be as follows: 24 autosomes, 1 larger and 1 smaller mono- 

 some and 4 diplosomes, a total of 30 elements which was the number constated to be 

 present there. 



Literature. — In my earlier observations (1901?>) I mistook the larger monosome of 

 the growth period for a plasmosome, because I supposed a plasmosome must be present ; 

 what I then called the "univalent chromatin nucleolus" corresponds to what I now 

 denominate the smaller monosome ; and I correctly showed that this does not divide in 

 the first maturation mitosis. The following mitosis was not described. Otherwise 

 the complex phenomena were correctly ascertained. 



39. PfEciLocAPSus GONiPHORUs Say. 



Growlli Period. — This is terminated by a complete rest stage. Attached to the 

 plasmosomes {PI, Fig. 288, Plate XIII), though occasionally separated from them, are a 

 ninnber of safraninophilous dense allosomes. The largest of the.se {di. 1) is alwa3's in 

 the form of a pair of short parallel I'ods, and, therefore, is to be regarded as probably 



