SEXUAL ACTIVITIES OF THE SQUID 409 
meaning. It can in no way be compared with the prostate 
gland of vertebrates. The inner walls of the gland are marked 
by various connecting ridges which project into the large cavity 
of the gland. The gland forms a blind sae with only one duct. 
Only the end of the spermatophore that contains the sperm 
mass is pushed back into the hardening gland, and, as has been 
said, when the spermatophore is pushed into this gland the 
outer tunic is always present. 
The connecting duct between the middle tunic gland and 
the hardening gland is relatively small, but the walls are highly 
glandular. The duct forms a bent cylindrical tube with a lumen 
that corresponds pretty well with the diameter of the sperma- 
tophore. I have not succeeded in removing spermatophores 
passing through this portion without injuring them and in sec- 
tions the injury of the spermatophores is usually considerable. 
I find, however, that the material of the outer tunic is present 
on parts of the spermatophore that have not reached the harden- 
ing gland, so this narrow gland must be reponsible for its forma- 
tion. It may therefore be called the outer tunic gland (figs. 
29 to 33, OTG). Inasmuch as spermatophores are seldom found 
in this gland, they probably pass through it rather rapidly. 
The end containing the sperm mass is passed back into the 
hardening gland to about the level of the cement body. The 
region of the cement body and ejaculatory apparatus never 
enter this gland. The aboral end of a spermatophore, when 
present in this gland, projects into its lumen from the narrow 
outer tunic gland without touching its walls. The sperma- 
tophore has definite outlines, the outer tunic is fully formed 
and not sticky, and the liquid in the lumen of thegland is trans- 
parent and not noticeably viscid. When the gland is opened 
in sea-water, the secretion that mixes with the water is visible 
only because it has a different refractive index. It mixes readily 
with the water and disappears. In sections of the organ the 
contents of this gland frequently show some coagulated and 
stained material which probably comes from the secretion. 
While the aboral end of the spermatophore is in the harden- 
ing gland the oral end is passed along the outer tunic gland. to 
