LIFE HISTORY OF THE BLUE CRAB. 123 
more advanced stage. On July 9 another crab threw out a few eggs and on July 28 
another spawned. In another similar experiment, two crabs were found to spawn. 
These experiments show that the female crabs spawn twice or more times during 
the course of their lives. The successive lots of eggs are fertile and will hatch. Enough 
spermatozoa are stored in the sperm sacs of the female at the time of the one copulation 
which she undergoes to fertilize all the eggs which she lays. 
It is evident, also, that the adult female crabs found on the bottoms in the southern 
part of Chesapeake Bay during the winter are not spawned-out or barren crabs. On 
the contrary, part of them are individuals which have mated the previous summer and 
will lay their first lot of eggs the next season, and part are crabs which have produced 
one or more sponges the preceding summer and will survive the winter and lay again 
the succeeding season. Most of the females lay one or sometimes two lots of eggs 
the first season, one toward the early part and the other (when this occurs) later on, 
survive the winter, and lay again the next season. Some lay the first lot late in the 
summer and one or two batches the succeeding season. 
Of course a crab will not spawn indefinitely and just as surely it must finally die. 
The ovaries of some of the crabs which spawned in captivity were found to contain no 
more eggs, however small. Evidently such crabs had spawned out and would produce 
no more sponges. Crabs whose ovaries are in this exhausted condition are found during 
the summer among those taken for market. As the ovaries of none of the 238 individuals 
examined during the winter were in this condition, it seems probable that the female 
crab dies shortly after having produced her last lot of eggs. This probably occurs 
during the late summer or early fall. As mentioned earlier, this is, no doubt, one 
of the causes for the falling off in the available supply of crabs in the southern part of 
Chesapeake Bay during August of each year. This decrease is manifested in the 
curves of the averages of the daily catches of the 14 years for which the data were worked 
out. A typical curve is shown in text figure No. 2. 
WINTER HABITS. 
It has usually been thought that during the winter the crabs retire to fairly deep 
water and bury in the mud or sand. It is very apparent that this view is in part correct. 
Most of the crabs proceed to the deeper water to pass the winter. The author is 
reasonably sure, however, that the majority of the crabs do not bury in the substratum. 
This, at least, is true of those found in the waters where dredging is carried on. The 
author has been told of cases in which crabs were found buried during the winter in 
the mud of a shallow cove or creek, but has never had the opportunity of verifying 
such statements by personal observations. 
If one judges from the appearance of the hauls made while dredging, the crabs 
brought up have not been buried. This is especially true in cases where the dredging 
was being carried on over fairly hard, sandy bottoms. Many observations were made 
when the teeth of the dredges were so clogged with seaweed that they could not possibly 
be sinking into the comparatively hard sand, even if it is supposed that the crabs could 
have buried init. Crabs were being brought up in average quantities. Many dredgers 
