ANDREWS: ANNULUS VENTRALIS. 
451 
500 in larger females and as many as 631 in a very large female. After 
laying, the number of sperm left behind in and upon the annulus was 
roughly estimated from surface views and sections to be some 10,000, 
most of which were in the recess. All these were thought to be of no 
use, for when an annulus with its large remnant of sperm was removed 
from a female about twenty-four hours after the eggs were laid the eggs 
developed and hatched in fifty-one days just as did those of a control 
in the same aquarium. 
Before laying, the amount of sperm within the annulus is very much 
greater and some estimate of the number of sperms stored there was 
obtained by the following means. An annulus was dried with filter 
paper and dissected under the microscope to remove the sperm plug 
with adherent sperm. In a drop of strong potassic nitrate solution 
the sperms oozed out and dispersed through the liquid so that their 
number could be roughly estimated and it was found to be about 
35,000. Again, such a plug was put into a minute drop of water on a 
circular cover 7 mm. in diameter till most of the sperm had dispersed, 
then transferred to a second cover and washed about to remove the 
remaining sperm. Rubbing the two covers together distributed the 
sperms uniformly and they were then dried and stained with dahlia 
as smear preparations. The sperms were then counted over one half 
of each cover and the number estimated for one female was 14,814, for 
another 19,372 and for another case when four covers were used 
25,636 were estimated. The last was probably less inaccurate than 
the other two. In this method, the sperm from the recess and from 
the posterior end of the trumpet tube was not obtained and the above 
numbers must be too small. By counting several areas in each of 
twenty successive sections through the annulus of a female killed in 
December when the annulus was already full of sperm, a much larger 
estimate, 50,000 to 60,000 was obtained. 
We conclude that, while some thousands of sperms may remain 
within the annulus after the eggs are laid, many more thousands are 
discharged when the few hundreds of eggs are flowing by and 
thus there is numerically ample supply for the fertilization of all 
the eggs. As a matter of fact, very few of the eggs, even in con¬ 
fined specimens failed to develop unless from reasons obviously 
not connected with the amount of sperm. Unless parthenogenesis 
occurs we must conclude that all the eggs are necessarily fertilized as 
a result of the above described discharge of sperm from the annulus. 
