STRUCTURE OF THE MALE DUCTS. 
207 
I think these nuclei are probably the degenerating remains of the nuclei 
in the walls of the sperinatocysts, and which I regard as the mother 
nuclei of the spermatoblasts. 
Vasa deferentia of locusts. — These are long, nearly cylindrical tubes, 
the walls of which are composed of an interior lining epithelium and an 
external layer hardly one-fourth as thick as the epithelium, and com- 
posed of connective tissue and tracheae, and, as far as I have been able 
to observe, entirely without muscular fibres. The epithelium is formed 
of cylindrical cells, with large and distinct nuclei in the basal third of 
each cell. It is interesting to compare these ducts with the correspond- 
ing canals of Crustacea, the histology of which has been recently studied 
by Grobben 289 and by August Gruber. 290 It now seems probable that fur- 
ther observations will soon render it possible to give a description of the 
minute structure of the male ducts which shall correctly record the typ- 
ical form among arthropods. 
Ductus ejaculatorius of locusts. — If we make a transverse section 
Jthrough the abdomen of a male C. femur -ruorum at the level where the 
'ejaculatory duct runs straight along underneath the dorsum a section of 
the duct will be obtained of the appearance indicated in the unfinished 
drawing Fig. 33. The canal of the duct, Ej. D, is oval. Below, on either 
side, is the section of a large trachea, Tr. and 2V 1 . The duct itself is 
lined by an epithelium, Ep., the height of which is very great at the 
sides of, but inconsiderable above and below the duct, so that while the 
cavity appears oval in section the external outline of the epithelium is 
more nearly circular. Above and below, where the epithelium is nar- 
row, there is but a single row of nuclei, but in the broad lateral portions 
the nuclei are at very various levels, though never outside a certain cen- 
tral zone of the cells, so that just below the inner, and likewise the 
outer, surface of the epithelium there is a clear space in which there lie 
no nuclei. The epithelium is surrounded by a muscular coat, Muc, of 
circular fibres, which form a layer of considerable thickness. This coat, 
as will be seen from the figure, is not really separated by the neighbor- 
ing connective tissue. In fact, the external limits of the wall of the duct 
are not defined. 
Vesiculae seminales of locusts. — These are bbnd cylindrical tubes of 
larger diameter than the vasa deferentia. They consist of an upper, 
wider, non-muscular, and a narrower lower division that has a muscular 
coat. The passage from the upper to the lower portion is gradual, not 
sudden. 
A section through the upper part, Fig. 31, shows that its walls are 
formed mainly by a cylindrical epithelium, with slightly oval nuclei, 
nearly in the center of each cell. I think, but am not sure, that the nu- 
clei are nucleolated. There is a delicate interior cuticula. I thought 
285 Grobben : Eeitriige zurKenntniss dcrraannl. Gescblecbtsorg. der Decapoden; etc. Arb. Zool. Inst. 
Wion. (1878). 
290 A. Gruber: Tiber zwei Siisswasser Calaniden, Leipzig, 1878. Beitrage zur Kenntniss der Genera- 
tioDsorgano der freilebenden Copepoden. Z. Z., xxxii (1879), p. 407. 
