the Echinoderm Egg during Fertilisation. 



221 



1'5 c.mm. of oxygen in 10 minutes, after fertilisation consumed 56 c.mm. in 

 this time ; there was thus an increase in the respiratory quotient of the eggs 

 in 10 minutes after fertilisation of something like 37 times that of 

 the unfertilised condition. If we consider the increase taking place at the 

 end of the first minute after the addition of the sperm to the eggs, we get 



5 MINUTES. 10 



Fig. 2. — Graph showing the amount of oxygen taken up and the carbon dioxide given 

 off during the fertilisation of a quarter of a million (2'08 mgrm. egg N.) eggs of 

 E. microtuberculatus. It will be seen that this graph is similar in all respects with 

 that shown in fig. 1, except that it is half the size of the former, half the quantity 

 of eggs being used. 



even more striking figures. The oxygen consumption of the unfertilised 

 egg is, we have seen (15 determinations), about 1'5 c.mm. oxygen for 

 4 mgrm. of egg nitrogen in 10 minutes, and in the case of the present 

 experiment a reading of this value was actually obtained on the unfertilised 

 egg. If we divide this figure by 10 we arrive at the value of the oxygen 



