Studies on Chromosomes 73 



w-chromosomes of the spermatogonia, but from two larger chro- 

 mosomes, while the spermatogonia! ^^-chromosomes are supposed 

 to be converted into the "accessory" (!). I will not enter upon the 

 very ingenious, if somewhat fantastic, conclusions that are based 

 on these results, for, as I shall attempt to show, the results them- 

 selves cannot be sustained in some important particulars. But 

 apart from this I am glad to be able to give the most positive con- 

 firmation of Gross's interesting discovery in regard to the numer- 

 ical relations m the male. Syromastes is indeed a case ui which 

 the spermatogonial number is an even one (tiventy-two), ivhile there is 

 a heterotropic chromosotne in the second division. Half the sperma- 

 tozoa seem to receive ten chromosomes and half eleven, as in so 

 many other species of Coreidae. But as Gross also correctly de- 

 scribed, the heterotropic chromosome is here a bivalent which 

 represents two chromosomes united together. The true numbers 

 characteristic of the two classes of spermatozoa are therefore 

 ten and twelve, respectively. For the sake of clearness I will here 

 point out that this becomes at once intelligible under the assump- 

 tion that the female number is not twenty-two, as Gross believed, 

 but twenty-four; and such I believe will be found to be the fact. 

 That Gross was mistaken — doubtless misled by the earlier 

 conclusion of Paulmier ('99), in which he was at first followed by 

 Montgomery ('01) — in supposing that the chromosome nucleolus 

 of the growth period divides to form the m-chromosomes, is I 

 think thoroughly demonstrated by my preparations. In the case 

 of Anasa and Alydus I showed ('05c) that the m-chromosomes are 

 not formed in the way Paulmier believed, but arise from two small 

 separate rod-like chromosomes that are in a diffused condition 

 during the growth period and only condense to form compact 

 bodies at the same time that the condensation of the larger chro- 

 mosomes takes place. I have since found this to be true of many 

 other species. It is confirmed in the case of Anasa by the smear 

 preparations of Foot and Strobell ('07), and I have also since fully 

 established the same conclusion by this method, by means of 

 which every chromosome in the nucleus may be demonstrated.^ 



* This is opposed to the conclusion of Montgomery ('06). 



