224 BUNTING. [Vou. IX. 
not segment, which was probably due to the unusual heat to 
which they were subjected. 
Colonies that had been observed under normal conditions 
on August 17, were placed upon the ice the night of August 18, 
at 8 p.m. Removed from the ice at 9.30 a.m. on August 19, 
when the eggs and spermatozoa were discharged; these eggs 
segmented normally at 11.10 A.M. 
The experiment of lowering the temperature was tried again 
on August 19. The shells with the colonies upon them were 
removed in three series on August 20; one at 8 a.m., the 
second at 10.30 A.M., while the third at 2.10 p.m. In the first 
series, eggs were laid, and segmentation started in about an 
hour to an hour and a half after removal from the ice, while in 
the second and third, immediately upon removal from the ice 
the eggs were deposited and segmentation commenced. 
On August 20, the experiment was again repeated, the 
removal from the ice being done at different periods of time. 
The outcome of these experiments made it possible to watch 
the segmentation by daylight, and the material could be studied 
at different times. This was of importance, since one of the 
serious difficulties had been that the cleavage began simultane- 
ously in almost all of the eggs, those which had been belated 
proving unsatisfactory for observation. This method of placing 
the entire colony upon ice some time before the period at which 
the eggs were to be discharged, was suggested by Mr. Bristol, 
who had tried it with some success on other forms. 
Through various experiments in the summer of 1891, the 
time for the normal deposition of the eggs seemed to be at 
about 10 o’clock p.m.; therefore, at that time they had been 
carefully examined by lamp-light, and it was found that about 
11 o'clock was the time at which normal segmentation took 
place. The fact that the colonies had been subjected to-strong 
light, after having been kept in the dark, both in this case 
and in that when they were placed upon ice, led me to question 
whether the discharge of the ova and spermatozoa could be 
due to the effects of the light. Therefore, immediately upon 
removal from the ice some colonies were placed in complete 
darkness. Upon observation, later, it was discovered that this 
