56 
Lot C.- — Y ery cold; hail and rain. The eggs from several 
ripe females v .re fertilized, bnt no changes followed, and all 
the eggs soc a decayed. 
.A noth' i* lot of embryos, which were about three days old, 
and in the stage shown in Plate III, Figure 38, also died. 
Lot. D. — Day quite cold. The eggs from three females 
were very carefully fertilized with a mixture of the semen 
from three males at 10 A. M. About one in one hundred 
commenced segmentation between 1 and 6 P. M , and devel- 
oped very slowly. The next day all were dead. As the eggs 
were perfectly ripe, and became covered with active sperma- 
tozoa, their failure to develop must have been due to the low 
temperature. 
Lot E. — Quite cool in the morning ; warm and sultry in 
the afternoon. Eggs fertilized at noon, and segmentation 
commenced in about two hours. At 7.30 P. M. about half of 
them had finished segmentation, and at 11.15 P. M. most of 
them were in the stage shown in Figure 32. On the fourth 
day most of them w T ere doing well, and had reached the stage 
shown in Figure 42, when a fall in the temperature killed all 
of them. 
Lot F. — Father warm. Eggs fertilized at 6 P. M., and the 
next morning at 5, or eleven hours after fertilization, some 
were in the stage 32, and some in the stages 36 and 37. 
Lot Gf. — Day quite warm. Eggs fertilized at 8 P. M. At 
10.15 P. M., or a little more than two hours after fertilization, 
nearly all of them were in the early stages of segmentation, 
and at 5 A. M., or nine hours after fertilization, they were in 
the stage shown in Figure 37, and in forty-eight hours they 
were in the stage 42. 
Lot H. — Y ery hot day. Segmentation was completed two 
hours after fertilization, and in two hours and a half the em- 
bryos were in the stage 32, and in forty-eight hours in the 
stage shown in 43. 
I w T as so far from the water during my investigations that I 
was not able to make any observations upon the temperature 
of the oyster beds during the spawning season, but the cases 
