SEXUAL ACTIVITIES OF THE SQUID 407 
It is much more like the mucilaginous material in the sperm 
mass, but it has not just the same staining properties. 
How these parts are formed is not known. Possibly the 
mucilaginous substance binding the sperm mass is continu- 
ous as a core and the cement substance and hyaline core are 
similar substances wound around the central core. If this be 
the case the mucilaginous gland must consist of two functional 
parts. 
A second point has to do with the spiral filament. This seems 
to lie directly against the hyaline core, with the inner membrane 
covering it. The space between the loops of the spiral filament 
which extends from the inner membrane to the hyaline core 
is evidently filled with some substance that never stains and is 
apparently liquid. The hyaline core never bulges much between 
the loops of the spiral filament, and the inner membrane is never 
pressed in much between these loops. With the pressure that 
is put upon the contents of the spermatophore when it is com- 
pleted—by the elastic outer tunic, even before the hyaline core 
disappears—there would be distortions were there not a support- 
ing liquid in this space. 
It is not difficult to understand how each of the layers described 
are formed when we bear in mind that each is wound around 
the slowly rotating mass as it proceeds through the duct. The 
invisible part, the part connected with the nervous mechanism 
that sees to it that each secretion is started and stopped at the 
proper time to make the whole a complete, well-formed com- 
plicated machine, is not more remarkable than many other 
nervously controlled mechanisms. 
The forming spermatophore has now passed well back into 
the middle tunic gland, and by the time the structures described 
have been completed the first formed end of the sperm mass 
lies near the distal end of this gland. 
As previously stated, the structure of the middle tunic gland 
(figs. 29 to 36, MTG) is essentially the same as that of the ejac- 
ulatory apparatus gland. The middle tunic is formed by wind- 
ing a sheet of secretion around the rotating mass as in the mem- 
brane described. There is a little liquid between the middle 
THE JOURNAL OF MORPHOLOGY, VOL. 32, NO. 2 
