ON THE SPERMATOGENESIS OF THE SILK-WORM. 
12 7 
and the left side of the dorsal vessel over the alimentary 
canal, in the segment where the sixth stigmata opens (namely 
eighth segment) and are firmly attached to the body-wall by 
the trachea of the sixth stigmata and fatty tissues. As in 
other Lepidoptera, each testis consists of four blind tubes or 
testicular follicles, which are covered with a common envelope, 
tunica adventitia, and each is placed facing the other with 
the concave side, on both sides of the dorsal vessel. From 
the middle of the concave side of each of these testes one 
vas deferens arises, and the testicular follicles enter into it. 
These ducts run, at first, along the dorsal side of the body, 
gradually changing their course into the ventral side, and 
finally attach themselves with a uterus-shaped process (fig 3) 
found on the ventral median side of the twelfth segment. This 
process seems to be changed into seminal vesicle, accessory 
glands and ductus ejaculatoris. 
In the female organs, all the relations are nearly similar 
to that of the male except the shape of the ovary and the 
mode of the attachment of the oviducts with it. The ovary 
of the silk-worm is smaller than the testis from the early 
beginning till to the last of the larval stage. It is somewhat 
triangular in shape, and is situated each side facing the other 
with a side of a triangle, the angles opposite to these sides 
being produced to form the oviducts. 
This is the usual form of the genital organ of Bombyx 
mori in its larval stage (Fig. 1—2). Cases are, however, 
met with where the vas deferens arises from the outer side 
of the testes as in the ovary, or one of the testes with its 
vas deferens on its inner side and the other on the outer side. 
Terminology. The question of nomenclature presents some 
difficulty, since so many different names have been given to 
the same elements by different observers. So far as I could, 
I have tried to avoid the use of such general terms as “sper¬ 
matoblast,” ‘‘spermatocyte,” “spermatogone,” etc. and have 
substituted simple descriptive expressions, as has been done by 
O. Hertwig, C. Ishikawa, and vom Rath. We may distinguish 
four stages in the sperm-formation of Bombyx mori. The 
first of which, we may call the formative stage (“ Keimzone ” of 
German authors), the second the growing stage (“ Waschsthums- 
