SEXUAL ACTIVITIES OF THE SQUID 397 
The adhesion of the end of the middle membrane to the mid- 
dle portion of the cement body not only serves to draw this 
cement body around the end of the sperm mass, but holds the 
sac in position to have the spermatozoa thoroughly and completely 
forced into it by pressure behind. It will be noticed that dur- 
ing this process the diameter of the aboral end of the spermato- 
phore is greatly reduced, due to the elasticity of the outer tunic, 
and that the middle tunic swells, loses its granular appear- 
ance, and comes to occupy the space vacated by the sperm mass. 
At the same time the outer end of the evaginated ejaculatory 
apparatus becomes considerably expanded as the sperm mass 
is crowded into it (figs. 12, 13, and 14). 
Continued pressure causes the walls of the cement body to 
burst (fig. 15). The end of the middle membrane is thus re- 
leased and the sperm mass enclosed in the reflected inner tunic 
and outer membrane, smeared with cement from the ruptured 
cement body on its larger closed end, glides rapidly through 
the middle membrane and is free from all other mechanisms. 
The covered sperm mass, which may be called a sperm res- 
ervoir (fig. 17), is usually somewhat coiled. The closed end 
is large and covered with cement, and the open end is small, 
with a thickened portion just behind the opening. The thick- 
ened portion seems to correspond to the thickened portion of 
the inner tunic and outer membrane, described in connection 
with the structure of the spermatophore, that lies a little aboral 
to the free end of this membrane. The thickened walls prob- 
ably tend to prevent too rapid escape of the spermatozoa. 
From the open mouth of this sperm reservoir of untreated 
specimens the spermatozoa escape in a constant cloud which 
reminds one of the smoke from an evenly discharging factory 
chimney. The discharge may go on for hours. When care 
is taken to provide an abundance of sea-water, such reservoirs 
will still be discharging twenty-four hours and more after they 
were liberated from the spermatophores. 
Referring to the methods of copulation of the squid, given in 
a former paper (Drew, ’11), it will be seen that when the sper- 
matophores are carried to the mantle chamber of the female 
