I42 ON THE SPERMATOGENESIS OF THE SILK-WORM. 
selben sich ansammeln, während der übrige Inhalt durch 
länglich ausgezogene Tröpfen gegeben ist, die sich zu varicösen 
Fäden anreichen.” 
Let us now compare Verson's results with mine above de¬ 
scribed. The description in his first paragraph is certainly that 
of my primary germ-cells. The second is also primary germ- 
cells in their later stages. The third and fourth are the cells of 
the growing stage and similar to my sperm-mother-cells. The 
“ komma- oder hufeisenförmig gestaltete Körperchen ” in the 
nucleus are undoubtedly derived from a bad preservation of the 
materials, and seem to be caused by coagulation of the chro¬ 
matin granules in the granular stage of the nucleus in young 
sperm-mother-cells. The fifth and sixth are the cells of the 
ripening stage. Just, as Verson stated, the sperm-mother-cells 
are generally arranged peripherally round the inner side of a 
cyste in a row, while after the first division such an arrange¬ 
ment is completely destroyed. Between the two successive 
divisions of the sperm-mother-cells no nucleolus appears in a 
nucleus. Consequently his description “ ihre Kerne schliessen 
häufig scharf markirte Kernkörperchen ein ” seems to be due 
to his mistaking the coagulated mass of chromosomes for the 
nucleolus. The seventh and eighth are the stage of metamor- 
ph osis. In this stage, he also mistakes the coagulation of the 
chromosomes for a nucleolus. 
In general, his result agrees with that of my own investiga¬ 
tion, though in the details it differs very much, probably in con¬ 
sequence of his defective methods of investigation. 
Spindle Figures, “Nebenkern,” Centrosomes 
and Nucleolus. 
As to the origin of the achromatic spindle, many facts have 
been observed by eminent naturalists such as van Beneden, (1) 
Flemming (7), O. Hertwig (19), Plainer (25), Strasburger (33, 34), 
Hermann (17), Bovevi (2), Brauer (4), Waldyer (40), Rabl, (29) 
Watase (41) Scliewiakoff (3), Ishikawa (21, 22) and many others, 
in different animals and plants. In general, there are, as far as 
my knowledge goes, three views as to its origin : (1) the achro¬ 
matic threads arise chiefly from the cell protoplasm ; (2) they 
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