Spermatophore of Dardanus asper — Matthews 
263 
Fig. 12. Cross section through region h of the vas 
deferens (Fig. 5). a. Stalk-forming epithelium; b, stalk; 
c, deepened groove of lumen; d, pear-shaped ampulla, 
(55X.) 
the thinner portion of the pear-shaped lumen 
occupies a position nearer the inner edges of 
the coils. The sperm column is molded in 
compliance with the pear-shaped lumen by 
muscular contractions of the walls of the vas 
deferens. When the sperm column is viewed 
through the wall of the vas deferens, only the 
thicker portion (Fig. lOb) is visible, hence the 
sperm column appears to be segmented. Each 
future ampulla of sperm is composed of an 
arch (10^^). These are connected by the sperm- 
column sheath (10c). The fate of the connect- 
ing sheaths is shown later. 
As the last compact coils of the left-handed 
helix (Fig. 5g) are traversed and the region 
of the flattened spiral (5^) is entered, the 
groove of the pear-shaped lumen deepens. 
The activity of the epithelial cells at the base 
of this groove now produces a new secretion. 
This at first is thread-like, but in the more 
distal portion of the flat spiral (Fig. ^h) thick- 
enings appear. The contents of the dissected, 
flat spiral which are shown in Figure 11 reveal 
that this secretion {a) accumulates at definite 
regions {b, c, d, e) between the closing arches. 
The thickenings form short, blunt stumps 
{d, e) which are the precursors of the stalks 
(Fig. 15c). The importance of the connecting 
sheath (Fig. 10c) is now apparent. As the 
closing arches move distad in the deep groove 
of the vas deferens, the stalk-forming material 
accumulates only in the regions between the 
closing arches; the connecting sheaths be- 
Fig. 13. Cross section through region i of the vas 
deferens (Fig. 5). a, Stalk-forming epithelium; b, stalk; 
c, veil-producing epithelium; d, veil-producing secre- 
tion; e, ampulla of sperm. (55 X.) 
tween adjacent ampullae prevent the stalk- 
forming material entering the lumen. By mus- 
cular contraction of the walls of the vas 
deferens, the arches finally close, but not until 
the stalk-forming material has^ accumulated 
between them. 
In the region distad to the flattened spiral 
(Fig. 5/), a cross section (Fig. 12) reveals that 
the stalk (Jb) in the deep groove of the lumen 
(c) lengthens both by continued secretion by 
the epithelial cells {a) and by the muscular 
activity of the walls of the vas deferens. 
The lengthening of the stalks carries the 
ampullae of sperm ” aloft,” and the connecting 
sperm-column sheaths between adjacent am- 
pullae become extremely thin and finally ob- 
scure. 
As this lengthening process continues, a 
more distal cross section (Fig. 13) reveals that 
the epithelial cells (c), which line the deepened 
groove of the lumen, produce still another 
