372 Edmund B. Wilson. 



was described as showing but seven chromosomes) or might remain 

 separate during this division (in which case eight separate chro- 

 mosomes appear). I soon found, however, that in Lygaeus and 

 Coenus whole cysts differed in this respect, all of the cells of a given 

 cyst constantly showing one number or the other. With this is 

 correlated the fact that in the anaphases of the second division 

 no accessory chromosome in the usual sense of the term is present, 

 all the spermatid-nuclei receiving the same number of chromo- 

 somes, namely, seven, which ishalf the spermatogonial number in 

 both species. Further study conclusively showed that in both of 

 the species the cells with eight chromosomes were primary sper- 

 matocytes undergoing the first maturation-division, while those 

 with seven were the secondary spermatocytes undergoing the 

 second division. Of this fact no doubt can exist, since the second- 

 ary spermatocytes are much smaller than the primary ones, the 

 spindles are shorter, the chromosomes only half as large, the meta- 

 phase-figures are often found in the same cysts with the character- 

 istic late anaphases and telophases, and all the stages of both 

 divisions were found in abundance. Though a great number of 

 division-figures have been examined, I have never seen seven 

 chromosomes in the first division in any of the forms examined; 

 and though I will not deny that Montgomery may be correct in 

 the statement that such forms occur, I believe he was misled on 



most successful preparations are from material fixed with strong Flemming's fluid, and stained with iron 

 haeraatoxylin followed by long extraction, in some cases followed also by counter staining with Congo 

 red or orange G. These show the cytoplasm completely decolorized, the chromosomes intensely black, 

 and with outlines of such regularity and sharpness that the most careful camera drawings give the appear- 

 ance of being schematized. A few very fine series were stained with Zwaardemaker's saflranin (which 

 gives a splendid transparent stain). Many others were fastened to the slide unstained, and some of 

 these I have stained with saffranin and gentian violet (the method recommended by Montgomery) 

 which have given very valuable control results, especially in regard to the accessory chromosome and 

 plasmosome which in the earlier growth stages are not well differentiated by the hccmatoxylin. I am 

 much indebted to Dr. Paulmier's generosity in placing at my disposal this valuable material, to which I 

 have since added many new preparations of my own. 



In a subsequent paper I shall describe the results of a re-examination of some of the maturation 

 phenomena in Anasa and Alydus, in both of which there is demonstrative evidence that the accessory 

 chromosome is not the small central chromosome or microchromosome ("chromatin-nucleolus" of Mont- 

 gomery), as Paulmier supposed in the case of Anasa, but the odd or peripheral one, precisely as Gross 

 ('04) has recently described in Syromastes. While looking over some of the other species for the sake of 

 comparison my attention was directed, first in the spermatogenesis of Lygaeus turcicus and Coenus 

 delius and afterward in that of Euschistus, Podisus and other forms, to the phenomena which form 

 the subject of the present paper. 



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