A ('omparative Stiuiy of the (’lironiosomes etc. 
263 
The J^-chromosome is conspicuous throughout the eiitire growth 
period. It can be seen as a deeply staining body in the early leptotene 
nuclei (Plate XX, Figs. 71, 72), and it soon applies itself to the nuclear 
inembrane at the side of the nucleus toward which the ends of the zygotene 
loops later converge, that is, at the positive pole of the nucleus. Here, 
in the early bouquet stage, it is seen as a rounded knob-like niass of chro- 
matin attached to a larger chromatic body, which is either flat or elongated 
into a rod (Fig. 80). A little later the a;-chromosome elongates and be- 
comes Club shaped, the narrow end pointing toward the positive pole of 
the nucleus, where it terminates 
in a mass of very deeply stain- 
ing chromatin. This mass of 
chromatin, in dose connection 
with the a>chromosome, is at first 
single, then it beconies bilobed 
(Plate XX, Figs. 83, 84), and 
usually divides into two, or 
sometimes three, chi’omatic nu- 
cleoli (Figs. 85, 86), which often 
remain in direct connection with 
the ic-chromosome (Plate XX, 
Figs. 89—93). As illustrated in 
textfigure A, the autosome loops 
do not come into dose contact 
with the «-chromosome, but they 
do converge toward the chro- 
matic nucleolus. AVhen this nu- 
cleolus breaks up into two or three nucleoli, each portion remains in 
intiniate contact with one or more autosomes by means of linin fibers 
(Plate XX, Figs. 85, 92, 93), which radiate from the nucleoli like the 
spokes of a wheel. Since these nucleoli usuaUy remain connected with 
the x-chromosome (Figs. 89, 90, 92, 93), they form a secondary means 
of connection between the x-chromosome and the autosomes. These 
chromatic nucleoli, deeply stained, are very conspicuous in the strepsi- 
nema until the autosomes become very hazy in outline; then they 
become more granulär, gradually give up their stainable substance, grow 
smaller, though still exhibiting radiating fibers (Plate XX, Figs. 94, 
95), and finally disappear before the tetrads arise (Fig. 96). The chro- 
matic nucleoli are doubtless those seen and figured by Boring (’07, 
p. 490, Plate IV, Fig. 113) and designated by her as m-chromosomes 
Textfigure A. 
Diagram of first spermatocyte of i'. curvata, basecl 
on Figures 82 — 84 (Plate XX), representing the end 
of the bouquet stage. Xine loops (actually double), 
the x-chromosome and the chromatic nucleolus are 
shown. 
