HEAT PRODUCTION BY EGGS. 347 



the beginning of the experiment. Whenever possible all of the 

 eggs used in an experiment were taken from a single female. 

 These were allowed to stand for a few minutes in a finger bowl 

 in a little more than 50 cc. of sea water. The finger bowl was 

 floated in running sea water. Remnants of the ovary and other 

 debris were removed from the finger bowl by forceps or pipette. 

 After a few minutes the eggs were stirred in the water so as to 

 be evenly distributed throughout the whole mass of water and 

 exactly 50 cc. of the suspension was transferred to flask (I.) by 

 means of a volumetric pipette. Also 50 cc. of sea water were 

 placed in flask (II.). The temperature of flask (II.) was then 

 made enough higher than that of flask (I.) so that at the end 

 of the run it would be about as much below (I.) as it was above 

 at the beginning. This made the value of the integral involving 

 6 a approximately zero and kept the maximum value of the 

 corrections low. The water-cap with a drop of dry sperm in 

 the fertilizing tube was then put into place, the cap filled with 

 water and the readings begun. The starting of the experiment 

 and the making of the observations and recording them occupied 

 the full time of two persons. Readings of the main thermopile, 

 6 a , were made every 60 seconds, and of the auxiliary thermopile, 

 6t>, every five minutes, for a period of from two and a half to 

 three hours. Experiments were in only a few cases continued 

 beyond the three hour limit. When steady conditions had been 

 reached and enough readings had been taken so that the heat 

 production of the unfertilized eggs could be determined, the 

 pipette was lowered until its tip was below the surface of the 

 egg suspension, the sperm washed out and stirred into the 

 suspension, and the pipette raised again. This operation seldom 

 caused an irregularity of more than 0.0005 C. At the same time 

 a sample of the same batch of eggs was fertilized in a finger bowl, 

 and kept surrounded by running sea water. These eggs were 

 examined from time to time. The galvanometer zero and the 

 storage cells for the potentiometer were checked frequently. At 

 the end of the run the average diameter of the eggs was measured, 

 in addition to the usual data on the percentage of fertilization 

 and development. The volume of the single egg computed from 

 the average value of the diameter, and the total volume of eggs 



