Processes of the Echinoderm Egg during Fertilisation. 419 



(b) Oxygen and Carbon Dioxide Determination. — 2 c.c. of the same lot of 

 eggs as those placed in the flask in above experiment were put in the chamber 

 of oxygen manometer and a drop of KOH put in the cup, 2 c.c. of plain sea- 

 water being placed in the control chamber. In a second manometer used for 

 control the same quantity of eggs were placed in the chamber, the KOH 

 being left out. 



Temperature of manometer bath 14'5° C, barometer 760 mm. The mano- 

 meters were put in position in the bath and after being brought into complete 

 equilibrium with the bath water the cocks of the manometers closed and the 

 eggs fertilized. The first manometer showed that : — 



At the end of 15 minutes the eggs had consumed 24 - 2 c.mm. oxygen. 

 » » 30 „ „ „ o3'0 „ „ 



„ 60 „ „ „ 44-0 „ 



At the end of the experiment eggs in the chamber showed 100 per cent, 

 fertilisation membranes and some commencing two cell stages. Kjeldahl deter- 

 mination on the eggs gave 4 - 07 mgrm. egg nitrogen present. 58 - 4 mgrm. of egg 

 nitrogen at this rate would take up 63T4 c.mm. oxygen, which is equivalent 

 to 0-902 mgrm. 



As 2"9 grm.-calories of heat were given off in the first hour following 

 fertilisation, for 58 - 4 mgrm. N in first part of experiment, 



Q - m* = 3 ' 215 - 



The heat production in this experiment was 10*5 grm.-calories in 5 hours ; 

 in 12 hours, 22-8 grm.-calories. 



In the second manometer 4 - c.mm. of oxygen seemed to be the difference 

 between the oxygen intake and CO2 output in this experiment, for 

 4 - 07 mgrm. of egg nitrogen. If we assume that 44'0— 4'0 gives us the amount 

 of carbon dioxide produced in this experiment, we get the respiratory 

 quotient of 40/44 = 0-91. 



It will thus be seen the carbon dioxide output of the eggs is almost as 

 great as the oxygen consumption. In all the experiments the carbon dioxide 

 respiration follows the oxygen consumption very closely, the respiratory 

 quotient varying from 0'9 to - 95 in different experiments. 



Experiment 2. 



(a) Heat Determination. — 800 c.c. of well washed ripe E. miliaris eggs in 

 sea-water placed in Flask No. 3, 763 c.c. sea-water placed in Flask No. 4 

 acting as a control. Under the conditions of the experiments with air 

 bubbling through both flasks and thermocouple junctions in position, and the 



