Studies on Chromosomes 73 



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

 mosomes, while the spermatogonial ra-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 in the male. Syromastes is indeed a case in which 

 the spermatogonial number is an even one (twenty-two), while there is 

 a heterotropic chromosome 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 ('o5c) 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. 5 



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



