CHROMOSOMES IX COREID HEMIPTERA. 119 



contentions l>y direct observations on insect spermatogenesis. 

 Arnold '08) from his observations on the spermatogenesis of 

 Ilydrnphilns piceiis concluded that there were no idiochromosomes 

 in that torin, although Miss Stevens has found these elements in 

 all tin Colcoptcra which she has examined (42 species). The 

 ol.jc. -lion "Mi-red by Foot and Strobell ('07) to the presence of an 

 odd mimlu-r of chromosomes in the spermatogonia of Anasa 

 Iritis, hence of an "accessory" chromosome and the replies to 

 tin- objr< ti .n have already been considered. The present work, 

 particularly the section dealing with the cleavage and early bias- 

 toil, -mi miclri, gives further proof that in this species, as well as 

 in the other three examined, the number of somatic chromosomes 

 in the male is one less than in the female. Gross, from hi> 

 studic- on .^yromastes mar^inatus ('04) and Pyrrhocoris aptcrns 

 '<" . ' oni hided that the "accessory" chromosome could have no 

 ell. it on sex-production in these two forms, for he believed that 

 the number of chromosomes is the same in both sexes 22 in 

 S\> \ and 24 in Pyrrhocoris. In the last named form his 



count- with the earlier ones of Henking ('91), though the 



lattet \\.i- uncertain of the spermatogonial number. Recently 

 ho\\<\ci \\ ilson ('096, 'oox/) has reexamined both these forms 

 and linds that in Pyrrhocoris, the male has one less chromosome 

 than the li male, /. <-., 23 instead of 24, while in Sryomastes, the 

 male ha- 22 as described by Gross but the female has 24 instead 

 oi _v I'yrrhocoris may thus be placed in the same class with 

 Mich tomis as Archinterns, A nasa and Protenor. Syromastes, how- 

 -. !- unique among the Hemiptera hcteroptcra in having a 

 l.i\alent "accessory," though a similar condition has been de- 

 l.\ Morgan ('09) in the homopteran, Phylloxera caryce- 

 is, \\hile Payne ('09) describes several cases among the 

 K.duxiid.c /';/<///(/. Rocconota, Conorhinns) in which the large 

 idiot htomo-ome (which represents the "accessory") is double. 



In addition to the objections cited above, a number of authors 

 ha\c cither expressed their doubts of the presence of two sorts 

 ot -pci inato/oa. or, while admitting the existence of such a 

 ilimoi phi-m, ha\c questioned its sexual significance. In recent 

 years, however, -\idence has been steadily accumulating in sup- 

 port ot the conclusion that a nuclear dimorphism of the sperm 



