A Comparative Study of the ('hromosomes etc. 
269 
VIII. Division of first Spermatocyte. 
A. Enchenopa binotata. 
In the metaphase of the first spermatcyte division there are seen 
in the equatorial plate ten chromosomes®) connected with one another 
by fine linin fibers (Plate XX, Figs. 126, 127). The macrochromo- 
sonie geminus is conspicuoiis on account of its size. Lateral views of the 
spindle show this pair extending lengthwise, also eight smaller geinini 
and the allosome pah’ (Plate XX, Figs. 122—125). UsuaUy it is ini- 
possible to see the longitudinal division of the chroinosomes, but it lias 
beeil possible to deinonstrate their quadripartite compositioii in a rather 
peciiliar and striking manner. Near the edges of material fixed in Her- 
mann’ s fluid, after staining first in alizarin and then in crystal-violet, 
when decolorizing with acetic acid, the chromosoines seein to give up 
the violet stain rather rapidly, but not the alizarin. The result, repre- 
sented in Figures 119 and 136 (Plate XX), shows each geminus to 
consist of four deeply staining rods. Sometimes (Plate XX, Fig. 119) 
the outline of the whole chromosonie, stained orange in alizarin, can 
be seen. ln such cases a comparison of the decolorized chromosome 
with a deeply staining one (Plate XX, Fig. 118) froiii the deeper por- 
tions of the material shows clearly which are the homologous chromo- 
sonies. üccasionally a small tetrad which has not yet contracted fnlly 
enters the spindle still retaining its quadripartite form (Plate XX, 
Fig. 128). Gross (’04b) has also found cases similar to this in Syromastes. 
The allosome pair (Plate XX, Figs. 128—135 xy) is characterized 
by the thick single strand connecting the two components, which show 
a considerable Variation in form. In such ceUs as Figure 136 (Plate XX) 
represents this pah’ has greater affinity for crystal-violet than any of 
the other chromosomes. The allosome pair stains deeply and falls to 
show any evidence of a longitudinal division. These characteristics in 
form and staining reaction are the same as those exhibited by this pair 
in the late prophase. While there is often a considerable difference in 
the form of the two components of this allosome geminus, it is impossible 
to decide by nieans of either size or form wliich of the two is the a;-com- 
ponent and which the i/-component. 
9) The discrepancy in the size of the chi-omosomes in different cells is due to 
tlie method of fixation employed. The relative sizes of the chromosomes in a single 
cell remain the same, but after fixation in Hermann’s fluid (Plate XX, Figs. 127, 
135, 137) the chromosomes appear larger than after the use of Flemming’s fluid 
(Plate XX, Figs. 126, 128, 129). 
