PINNEY: ORGANIZATION OF THE CHROMOSOMES 315 



IN I'HUYNOTETTIX MAGNUS. 



tachment is constant. In view of the lateral position of the 

 polar granules in the telophases of the spermatogonia and 

 their proximity to the accessory chromosome, I am convinced 

 that in the small bodies of condensed chromatin in figures 16 

 and 17, showing early spermatocyte prophases, we have the 

 direct product of two conjugating polar granules. Each polar 

 granule contains material from each chromatid, and conse- 

 quently, in the tetrads of the first spermatocyte, when the 

 division between chromatids is apparent, we have from the 

 union of two polar granules four bulbous thickenings at the 

 synaptic ends of the tetrad, which indicate also the location of 

 the spindle fiber attachment. Through the processes which 

 follow, these centers of condensation prove permanent ele- 

 ments, reappearing in the dyads of the ensuing telophase 

 (fig. 29). From these observations it appears that the polar 

 granules are permanent bodies, not undergoing marked phys- 

 ical change during the processes of the cell division. This 

 permanency of position, in the case of the polar granule, 

 seems to indicate the existence of a force which governs the 

 relative position of the constituent elements of the chromo- 

 some through its various changes. Such a function may be 

 ascribed to the linin thread which undoubtedly forms an im- 

 portant part of every chromosomal entity. 



The occurrence of condensations at the distal ends of the 

 chromatids occasionally observed in the spermatocyte tetrads 

 cannot be explained by the preexistence of similar condensa- 

 tions in the spermatogonial chromosomes, for such are lacking 

 there. 



It would be interesting as well as instructive if we could 

 determine definitely the function of these polar granules. Un- 

 questionably they are in some way concerned with the definite 

 polarization of the complex element to which they belong, and 

 their relations both to the spindle fiber and to synapsis is sig- 

 nificant. In consideration of this question Doctor McClung 

 has suggested a comparison of the polar granule in the sper- 

 matogonial chromosomes with the body from which the axial 

 filament of the spermatid grows. The analogy consists in the 

 fact that in both cases we have a small, definitely formed mass 

 of homogeneous chromatin located at one end of an elongated 

 membranous vesicle and marking the attachment of a movable 

 filament, but we are unable to judge the meaning of these 



2-Univ. Sci. Bull.. Vol. IV. No. 14. 



