Processes of the Echinoderm Egg during Fertilisation. 423 



large amount of heat ; others, again, will be somewhat immature, and will 

 consequently give off little heat as compared with the properly mature stage. 

 On the whole, from a number of experiments with the unfertilised egg, I am 

 inclined to think there is little difference between the value of Q in the 

 unfertilised, as compared with the fertilised egg, and that Meyerhof's conclusion 

 that it is the same for both is correct. In three successful experiments with 

 the unfertilised egg, the figure for Q obtained in the above described experi- 

 ment represents the mean, and it is worth noting that this value is slightly 

 smaller than in the case of the fertilised egg. 



Discussion. 



The Unfertilised Egg. — In the foregoing experiments it has been shown that 

 the oxygen consumption and the heat liberation of the unfertilised egg of 

 E. miliaris is remarkably small. In 1 hour, 1,000,000 eggs (8 mgrm. egg 

 nitrogen) only consumed 15'1 c.mm. of oxygen, and liberated at the same 

 time something of the order of - 067 grm.-calorie heat. If we divide the 

 heat liberation in 1 hour's time, expressed in gramme calories, by the oxygen 

 consumption in milligrams, we get a quotient which we may call the calorific 

 quotient. In the case of the unfertilised egg this quotient was found to be 

 3*07. Meyerhof, in Strongylocentrotus, using the Winkler method for estimating 

 the oxygen consumption and the direct method for measuring the heat produc- 

 tion, found this egg consumed 94:1 c.mm. of oxygen and liberated - 038 grm.- 

 calorie, under similar conditions. The value of Meyerhof's calorific quotient 

 (Q) varied about 2 - 8. 



The Fertilised Egg. — On the addition of the sperm to the eggs of E. miliaris, 

 there is an immediate oxygen consumption by the egg and a corresponding 

 increase in the heat liberated. At the end of the first hour of development 

 86 - 4 c.mm. of oxygen were consumed by 1,000,000 eggs (8 mgrm. egg K), and 

 - 397 grm.-calorie of heat was liberated. The CO2 output of eggs was almost 

 the same as the oxygen intake ; the respiratory quotient being in the vicinity 

 of 0'92. In Strongylocentrotus, Meyerhof found under similar conditions for 

 65 - 38 c.mm. of oxygen consumed a heat liberation of 0"247 grm.-calorie, for a 

 similar quantity of eggs. The calorific quotient in this instance again being 



2 - 6 to 2 - 8. In view of the large number of eggs that have to be used for 

 making a heat determination on the unfertilised egg, it is doubtful if much 

 significance attaches to the difference found between the calorific quotient of 



3 - 07 in the unfertilised egg, as compared with 3 - 2 in the fertilised condition. 



