402 / GILMAN A. DREW 
are passed. The sperm thread is here flattened between the 
ridges and wound edgewise so one edge becomes the center and 
the other edge of the surface of the spirally wound sperm mass. 
As the spermatozoa are covered by the secretion from the gland, 
the secretion along that edge which forms the center becomes 
a continuous core in which there are few spermatozoa, and the 
secretion on the flat applied sides of the sperm thread stick the 
successive loops of the coil together. The sperm mass, as coiled, 
does not lie with flat applied surfaces of the loops at right angles 
to the central core, but the edge applied to the surface lags a 
little behind the edge at the central core. The surface edge 
is accordingly nearer the cement body than the core edge. 
In longitudinal section the sperm mass thus appears like a 
series of small open funnels with the small ends directed toward 
the aboral end of the spermatophore. ‘The spaces between the 
funnels, together with the core that would occupy the small 
open ends of the funnels is filled with sticky material furnished 
by the mucilaginous gland. From the location of the ridges 
which serve to coil the thread, through the remainder of the 
mucilaginous gland and through succeeding glands, the sperm 
mass is rotated on its longitudinal axis by the action of the cilia 
in the groove in which it les. It is through this longitudinal 
rotation that the sperm mass, molded by the ridges between 
which it passes, is coiled into the form described. The sperm 
mass, coiled in this way, is usually called the sperm rope. It 
should be borne in mind that the coil consists of a single flat- 
tened strand and not a number of strands as is the case with a 
rope (fig. 23 A; SM). 
Spermatozoa continue to issue from the vas deferens and the 
sperm mass continues to form until the end first formed reaches 
some distance past the limit of the mucilaginous gland to a 
point about opposite the notch (fig. 32, C1). The sphincter 
muscle around the opening of the vas deferens then contracts 
and no more spermatozoa are allowed to enter. When the free 
spermatozoa are wound into the coil the charge of sperm for 
one spermatophore is complete and the sperm mass is in final 
form. , 
