450 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
in the vas deferens, it might be thought the period of discharge was 
not also a continuation of their protection from water but that they 
were now acted upon by water to some extent before they meet the 
eggs. However, it seems that the mucous secretion probably does 
protect the sperms from the action of water even after they are dis¬ 
charged from the annulus, for another annulus fixed in Flemming’s 
solution sixteen minutes after laying shows (pi. 45, fig. 19) the sperms 
in the unchanged form crowded out of the suture and spread over the 
annulus. Only a small part of the promontory is drawn, with the 
posterior line of the zigzag on the right covered by a dense mass of 
sperms and more and more sparsely scattered sperms over the sur¬ 
face toward the left. Some of the sperms show the characteristic 
Y appearance within the bowl or vesicle and they are in the normal 
shape as given by osmic preparations. The three large dark masses 
represented, were secretion spherules such as crowd the mucous mass 
and may be obtained by cutting open the ‘‘cement glands” of the 
pleopods. These sperm were all imbedded in a grayish coagulum, 
the fixed glaire or mucus, probably. 
It thus seems that the secretions of the female with her habits of 
laying, produce an environment for the sperms as they are discharged 
that protects them from the water while at the same time they are 
spread out in the path taken by the eggs on their way to be fastened to 
the pleopods. A secretion of the female guards the sperm in this last 
phase as a secretion of the male protected them before. 
The view that the secretion of the cement glands is a means to keep 
the sperms unchanged till they meet the eggs does not exclude the 
generally accepted view that it is a means of fastening the eggs to the 
pleopods. An attempt this season to decide this latter question with 
reference to Williamson’s (:04) claimed use of the pleopod hairs in 
crabs has led to grave doubt as to the extension of this view to the cray¬ 
fish; however, the problem of exactly how the eggs are attached to 
the pleopods in the crayfish remains unsettled (Andrews, : 06 b). 
The baffling question as to how the sperms and eggs unite, seems 
involved in the making of the outer case by which the egg is fastened 
to the pleopod and remains for the present undecided. 
Before considering the means by which the sperms are discharged 
from the annulus, we will show that though a great many sperms 
remain in the annulus, enough are set free to fertilize all the eggs. 
The number of eggs laid at one period is about 200 in small and 400 to 
