452 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
In this connection, it may be pointed out that there is ample provi¬ 
sion for filling the annulus. In captivity, at least, the males are long 
active in filling the annuli of as many females as they may find and 
they have abundant sperm for this purpose. In filling the annulus 
there seemed to be no loss of sperm and on the other hand the number 
of sperm in one millimeter of the middle part of the vas deferens of a 
male in March was calculated to be 16,452, by the above cover-glass 
method. As the entire length of each vas deferens was 60 mm., there 
were about 2,000,000 sperms available in the vasa deferentia at one 
time. The contents of three or four millimeters length of one vas de¬ 
ferens would fill the annulus of one female and the entire amount 
would fill from 30 to 40 annuli. 
Coming finally to the question of how it is that sufficient sperm is 
discharged from the annulus at just the right time to meet the eggs, 
there is evidence that a muscular act of the female associated with 
the secretion of glaire and the discharge of eggs is a prime factor. 
When the female remained upon her back in the period of egg-laying 
it was noticed that the fifth pair of legs was held stiff in a peculiar 
attitude with the tips bent backward as elsewhere figured (Andrews, 
: 04 ). The bases of these legs were concealed by the abdomen during 
laying but in one case where the abdomen was forcibly raised it was 
found that the peculiar transverse ridge on the sternum of the fifth 
thoracic somite (text-figure A), was firmly pressed against the pos¬ 
terior face of the annulus as late as sixteen minutes after laving. And 
a horizontal section of this annulus (pi. 45, fig. 19) shows the sperm 
spreading from the suture. By forcibly moving the legs it is found 
that the movable fifth somite can be forced to press its sternal ridge 
against the annulus. It is probable that the observed attitude of 
those legs is accompanied by such pressure of the sternal ridge 
against the annulus as was actuallv observed in the above case. 
To determine if pressure on the posterior edge of the annulus 
would cause it to discharge, three specimens that had not yet laid, 
were subjected to strong pressure against the posterior face of the 
annulus in situ, either by direct pressing with forceps or scalpel, or 
by pressing the fifth sternum against the annulus. In both ways and 
in all three specimens, there was a visible oozing of liquid from the 
suture of the annulus, which had previously been dried with filter 
paper. As the sperm, if discharged, was readily floated away and 
lost in preparation and as no success was obtained in attempting to see 
