312 THOS. H. MONTGOMERY, 



parable to the chromatin nucleoli of Insect spermatocytes. Possibly 

 a clue to the phy logen etic origin of the chromatin nucleoli might 

 be found either in the My r lap od a, or in the Insecta aptery- 

 gota. 



In the spermatogonia there was no sign of a sphere, but in 

 the cytoplasm of the resting spermatocytes a well-marked idiozome 

 sphere is present. The first stage in the formation of this structure 

 {Id.Z, Figs. 75, 80) found by me was in the early synapsis, before 

 the chromosomes had split longitudinally: in this case at the distal 

 pole of the cell body was seen a spherical mass, nearly homogeneous 

 in appearance, and staining very faintly. This position of the idio- 

 zome sphere at the distal pole of the nucleus is preserved up to the 

 monaster stage of the 1st maturation division. Earlier stages were 

 not seen. 



The idiozome sphere remains homogeneous and spherical up into 

 the telophase (Fig. 94), and then becomes more deeply stained (Figs, 95, 

 96, 126) and stains most intensely at the height of the rest stage of 

 the spermatocytes (Figs. 101, 103, 104, 106, 108—111, Plate 20; 

 Figs. 112 — 125, Plate 21). With haematoxyline-eosin and the Ehr- 

 lich-Biondi-Heidenhain method it stains somewhat more intensely 

 than the surrounding cytoplasm, while with the triple stains of Her- 

 mann and Flemming it colors only faintly; the best stain for following 

 its stages is prolonged treatment with iron-haematoxyline. Towards 

 the close of the telophase the sphere undergoes a change, which finds 

 its culmination in the rest stage: instead of remaining spherical it 

 takes on the peculiar form of a peaked hat or of a tea-cup (Figs. 103, 

 104, 110, Plate 20; Figs. 113—115, 117, 119, 124, Plate 21). This 

 process appears to be accomplished by the concentration of its sub- 

 stance at the periphery, the deeper stain of the latter portion being 

 then due to concentration of substance. Whether all of its substance 

 becomes thus peripherally disposed is somewhat difficult to determine, 

 on account of the curved outer surface of the periphery; but I think 

 it most probable that this is the case, since in some late telophases 

 the otherwise homogeneous sphere appears to contain a central clear 

 space at the same time that the periphery is becoming more deeply 

 stained (Fig. 99, Plate 20; Fig. 126, Plate 21). 



Did the sphere substance concentrate itself equally on all points 

 of the periphery, a hollow sphere would result. But this does not 

 take place: there is one point at which it does not concentrate, so 

 that the resultant form is that of a cup or hat. The form may best 



