A Comparative Study of the Chromosoraes etc. 
285 
With the loss of the polar arrangement of the autosomes (Fig. 212), the 
chromatic nucleolus divides and comes into close contact with the auto- 
somes, but still retains its Connection with the x-element. As the strepsis- 
tene stage advances (Fig. 213), the chromatic nucleoli become smaller 
(giving up their substance to the autosomes?). When the tetrad form 
is reached (Figs. 214, 215), only linin fibers, upon which the “t/-chroma- 
tin” was scattered, remain connecting the x-chromosome with the auto- 
somes. Since the rc-chromosome has retained some of its “^-chromatin”, 
it is attracted by the “?/-chromatin” now contained in the autosomes; 
but should the x-element lose all its “?/- chromatin”, it would be indifferent 
to the autosomes and behave entirely independently of them, as in 
Oedipoda (Büchner ’09), BrachystoJa (Sutton ’02), and Oryllus (Baum- 
gartner ’04, Brunelli ’09), Figure 215 represents the metaphase of 
the first spermatocyte division. The a>element is spherical, its future 
plane of cleavage is parallel to the axis of the spindle, Linin fibers connect 
it to the autosomes. As the autosomes separate (reductionally) the linin 
fibers pull the a>chromosome toward both poles and it lengthens (Fig. 217). 
Sometimes, as seen in Figures 162, 163 (Plate XXI), it breaks into 
two parts at this stage, but normally it passes undivided in late anaphase 
to one of the two daughter cells (a, Fig. 218). The second division 
(Figs. 219, 221) is equational and all the chromosomes (lying with their 
plane of division parallel to the equator of the spindle) separate simultane- 
ously. The spermatids resulting from the division of the second spermato- 
cyte a (Fig. 219) are represented in Figure 220, (a^ and a^). Fach con- 
tains half the ^c-chromosome and is “female determining”. Those coming 
from cell b (Fig. 221), represented by b^ und b^ (Fig. 222), contain no 
rc-chromosome and are “male determining”. Thus, in the distribution 
of the “aj-chromatin” the same end resuit is achieved in both E. iinotata 
and E. curvata (compare Figs. 208, 210, with Figs. 220, 222, respectively, 
Plate XXII), but the distribution of the “«/-chromatin” may be unequal 
in E. curvata, depending upon the breaking up of the chromatic nucleoli 
(Fig. 213). This, following the Suggestion of Wilson (’lla, ’llb) and 
Morgan (’ll), may off er a possible basis for the association with the 
a>element of characters borne by the “?/-chromatm” and situated in the 
a;-element or autosomes. 
E. binotata probably represents the allosomes in one of the least 
modified forms, phylogenetically speaking, and suggests that it may 
still be possible to discover scme difference between the components of 
the aUosome pairs in the growth period of the spermatocytes of such 
forms as the Lepidoptera. Transitional forms between such hetero- 
