ON THE SPERMATOGENESIS OF THE SILK-WORM. 
149 
In the first division of the sperm-mother-cells (“ Sperma- 
tocyten 1. Ordn.”), the twenty-eight chromosomes in the equa¬ 
torial plane of the spindle divide transversely, as stated above, 
and produce two rows. Both Henking and vom Rath affirm 
also the existence of two rows of chromosomes in the equator 
of the spindle of this stage. But this, according to vom Rath 
(28), is due to the doubling of the chromosomes in the growing 
stage of the sperm-mother-cells, while Henking (15) believes it 
to be formed by the double arrangement of the chromosomes, 
already existing, so that according to this latter author, the 
reduction of the number of chromosomes takes place by 
this division, which according to all other authors occurs by 
the second ( r >. 
The reduction of the number of chromosomes in the genital 
cells of plants has been worked over, so far as I know, only by 
Guignard (10). The mode of the reduction which he observed of 
Lilium martagon, however, differs entirely from that of animals. 
According to this investigator the reduction occurs without a 
nuclear division in a stage of the “cellules mère définisives” (pro¬ 
bably corresponding to the sperm-mother-cells of animals). My 
investigation on the formation of the pollens of Lilium tigrinum 
and Allium fistulosum is not in accordance with this, but shows 
much similarity with that of animals. This I trust will be 
soon published. 
Summary. 
i. A large cell in the blind end of the follicle which is de¬ 
signated by the name of “ Keimzelle” by Verson , is not a genital 
cell but a supporting cell which connects the genital cells with 
the follicular wall. It always has a large nucleus with finely 
granular chromosomes collected here and there and staining 
very deeply with hæmatoxylin, safranin, carmine, and anilin 
colours. 
(1) According to the investigations of Moore (24), the sperm-mother-cells of the 
rat contain sixteen chromosomes, which are reduced into eight, and “the reduction 
would appear more comparable to the type described by Guignard during the forma¬ 
tion of vegerable pollen, than, to that pointed out by Hcrtwig in the spermatocytes 
of Ascaris.” This however appears to me very improvable. 
