48 
their width and the more considerable the eireular muscular invest- 
ment becomes (fig. 52 d'). Finally this sphincter-like muscular 
wall arrives at a thickness which on each side equals that of the 
lumen of the duct. In addition to these eircular museular fibres 
very strong radial bundles have now developed, which are im- 
planted into the wall of these ducts and for the greater part take 
their origin from the bodywall. These latter bundles might act 
so as to cause the enlargement of the duct, whereas the eircular 
investment serves for its contraction. 
Finally the longitudinal ducts open into the posterior portion of 
the tubes AR A’R’ in the way represented in figs. 46 and 52, as 
do also the two lateral masses EE’. These latter consist of a 
complex of hollow tubes of more or less lobular appearance, as the 
figure 46, which is a schematie reconstruction of the whole series 
of sections through these organs and not a direct drawing after the pre- 
paration, sufhiciently shows. They too have an external muscular 
investment and an internal epithelium which is folded and has 
everywhere the same character. It is essentially glandular and 
a stroma of connective tissue appears to support the cells. The 
glandular secretion entirely fills up some parts of the ducts and 
has the appearance of a thick bundle of finely twisted slime-threads 
densely interlaced into a compact mass. It stains with pierocar- 
mine becoming faint yellowish red. In one of the specimens I find 
very close to the point of junction of the tubes d’, AA’ and ER’ a 
small number of singular bodies. I have figured one of them in fig. 59, 
which measured 63 a. They are tinged light yellow with a red centre 
by pierocarmine treatment and have a distant resemblance to the 
bodies that are formed in the prostate of higher animals. 
The point of junetion just mentioned is widened out into a sepa- 
rate vestibulum V (fig. 52), applied on the top of A and A’ and 
internally coated by a ceiliated epithelium. Not only in EE’ where 
it is replaced by glandular epithelium, but also in AA’ the char- _ 
acter of the tissue composing the walls of the organ considerably 
changes. We here find a very thick cellular coating apparently 
having a secretory function. The secretion appears finely granular 
