394 EDMUND B. WILSON. 



the chromatid body is intensely and purely stained by the 

 "nuclear" dye. In the Flemming material the intranuclear 

 plasmasome, sharply denned and uniformly present, is after 

 hsematoxylin alone pale yellowish, after both double stains clear 

 green. In the Bouin slides, as is often the case with material 

 thus fixed, the plasmasome stains with haematoxylin almost as 

 intensely as the chromosome-nucleolus, and in the earlier part 

 of its history is often indistinguishable from the latter. Un- 

 successful attempts were made to restain the Bouin slides with 

 the Biondi-Ehrlich and the Benda (mitochondrial) methods. 

 With the latter, both chromosomes and chromatoid bodies stained 

 alike with the crystal violet after every degree of extraction. 

 With the former method, neither of these bodies could be made 

 to hold the methyl green, both staining alike clear red. I think 

 it probable, however, that with suitable fixation these two kinds 

 of bodies could be differentiated by one or the other method. 



I. 



Without additional material, including smear-preparations, the 

 interesting history of the chromosomes can not be completely 

 elucidated, owing to certain difficulties in the early and middle 

 prophases. With exception of these stages however the relations 

 of the chromosomes are shown with a diagrammatic clearness 

 that leaves nothing to be desired; and they will be briefly 

 described, both for their own sake and because this is necessary 

 to a complete demonstration of the behavior of the chromatoid 

 body. 



The spermatogonial groups (Figs. 1-3) contain six chromo- 

 somes, the smallest number thus far recorded in any heteropteran 

 (in P. juniperina the number is 14, as in Euschistus). Two of 

 these may always be recognized as the largest. Of the remaining 

 four two, as the subsequent history proves, are the X- and Y- 

 chromosomes; but these differ so slightly in size that they can 

 hardly be distinguished with certainty at this time. The first 

 spermatocyte-division may be described as showing in polar view 

 four chromosomes (Figs. 4-6), including one large (B) and one 

 small bivalent (6), and the univalent X- and F-chromosomes; 

 but the latter lie close together, often in contact, and not seldom 



