Marshall—On the Anatomy of the Dragonfly. 777 
same irregularity and said: “the internal cavity of one of these 
tubules is very irregular”. 
Male Reproductive Organs. 
The two testes (fig. 39, T) are long and cylindrical. Each 
arises in the posterior part of the third abdominal segment 
to one side of and slightly dorsal to the mid-intestine. Each, 
in passing backward, shows at first a slight outward curve, this 
soon ceases and the testes run parallel to and along side of the 
alimentary canal to the posterior margin of the seventh seg¬ 
ment. From each testis there arises, in the anterior end of the 
eigth segment, a vas deferens which, continuing in the direc¬ 
tion of the testis, extends to near the middle of the ninth seg¬ 
ment. At this region each vas deferens suddenly turns inward 
and forward; after a short distance (less than the length of 
the segment) in this direction each suddenly bends once more, 
and, passing backward again the two approach and unite just 
over the common external opening which lies ventral and med¬ 
ian on the ninth segment (fig. 40). This last portion, that 
part from the final bend to the union of the vasa defferentia, 
is larger than at any other part and forms here, at the prox¬ 
imal end of each vas deferens, a seminal vesicle. 
A longitudinal section through a testis shows it to be made 
up of many cysts arranged in from one to three layers around 
a central tube which has a distinct wall of epithelial cells. 
This central duct starts back of the terminal cysts and runs 
longitudinally through the testis its continuation outside of 
which is the vas deferens (fig. 41). Leading into this main cen¬ 
tral tube are many small efferent ducts which carry the sper¬ 
matozoa from the cysts. 
The vas deferens shows in transverse sections that it is not 
completely filled with sperms there being a central rod-like 
mass of cells which passes through it. The cells composing 
this central core are similar in structure to .the epithelium. 
An examination of serial sections shows that at or near the 
place where the vas deferens leaves the testis there are prolonga- 
