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388 GILMAN A. DREW 
the tube formed by the middle membrane extending back from 
the concave side of the ball. 
The term ‘ejaculatory apparatus’ has been applied to the inner 
membrane, together with the spiral filament, the middle mem- 
brane, and the outer membrane and inner tunic to their junc- 
tion with the cement body. This is not a very satisfactory term 
as the spermatophore acts as a unit in ejaculation. That is, there 
is no one part that is active while the remainder are passive. 
The ejaculatory apparatus could not possibly deliver the sperm 
mass in position were it not for the elastic outer and middle 
tunies and their relations to liquids and structures. The term 
may, however, stand for want of a better one, since this portion 
is mostly concerned in ejaculation. 
It may aid somewhat in understanding the arrangement of 
the parts of a spermatophore if we consider what is present in 
optical cross-sections through: 1, the region of the sperm mass; 
2, the region of the aboral end of the cement body; 3, the region 
of the oral end of the cement body; 4, the region of the spiral 
filament, 5, the region just posterior to the cap. The parts cut 
will be mentioned in turn from the outside to the median axis 
(figs. 21 to 18). 
1. The region of the sperm mass: 1, Outer tunic; 2, middle 
tunic; 3, space (actual or potential) filled with liquid; 4, inner 
tunic; 5, sperm mass. 
2. The region of the aboral end of the cement body: 1, 
Outer tunic; 2, middle tunic; 3, space (usually actual) filled 
with liquid; 4, inner tunic; 5, outer membrane (if actually 
present fusee with the inner tunic), 6, inner membrane (prob- 
ably); 7, cement body. 
3. The region of the oral end of the cement body. 1, 
Outer tunic; 2, middle tunic; 3, space (usually actual) filled 
with liquid; 4, inner tunic; 5, outer membrane; 6, middle mem- 
brane; 7, inner membrane; 8, cement body. 
4. The region of the spiral filament: 1, Outer tunic; 2, mid- 
dle tunic; 3, space (actual) filled with liquid; 4, inner tunic; 
5, outer membrane; 6, middle membrane; 7, inner membrane; 
8, spiral filament; 9, lumen, probably filled with liquid, formerly 
filled with hyaline core. 
