36 J. W. SCOTT. 



and by "mechanical agitation." "The unfertilized eggs of 

 Amphitrite" he says, " develop to the trochophore stage if, after 

 residence in sea-water from one half to one hour, they be squirted 

 from a small nozzled pipette into another dish of sea-water." 

 "The method is an uncertain one," depending upon "state of 

 ripeness," and a " previous residence in sea-water or in one of 

 the sea-water-salt solution mixtures is essential." He had 

 noticed that some eggs are very sensitive to " mechanical manip- 

 ulation," but rarely develop when treated " immediately after 

 they are cut out of the body of the animal." 



Already convinced that there was a time-factor to be consid- 

 ered, I planned the following series of experiments. In each 

 series a set of eggs, removed from a single female at the same 

 time, was used. Due precautions were taken to prevent fertiliza- 

 tion by previously washing the female thoroughly in fresh water. 

 The hands of the operator, the dishes and pipettes used, were 

 carefully sterilized in the same way. For the same reason, sea- 

 water was used which had been raised to a temperature of 60 C., 

 cooled and aerated. After washing in fresh water, the Amphi- 

 trite was placed in a dish of sterilized sea-water until the eggs 

 were removed. In the following four experiments the eggs were 

 removed from the female at 2.10 P. M. July 30, and were at once 

 transferred very carefully to fresh sterilized sea-water. 



Experiment I. The object of this experiment was to test the 

 effect of transferring from one dish to another. In order to get 

 a standard amount of agitation, the eggs were allowed to fall, one 

 drop at a time, from the mouth of a pipette held one inch above 

 the water. The different lots of eggs and the time each was trans- 

 ferred are given below : 



1 control, transferred 2:IO P. M. 



2 transferred 2:27 P. M. 



3 " 2:43 P. M. 



4 " 2:58 P. M. 



5 " 3:13?. M. 



6 " 3:43 P. M. 



7 4:13 I J - M. 



8 4:43 P. M. 



The dishes containing the transferred eggs were left undis- 

 turbed until 10 P. M., when eggs were taken from i, 2, 4, 6, 8 



