192 



THE PHYSIOLOGY OF REPRODUCTION 



carried a step farther l by the employment of a special type of the 



manometer, in which it was pos- 

 sible to bring about the fertilisa- 

 tion of the eggs within the closed 

 chambers of the apparatus. It 

 was then possible to observe the 

 respiration of the egg at the actual 

 moment of entry of the sperm. 

 The eggs and sperm of Echinus 

 microtuberculatus were used. On 

 the addition of the sperm to the 

 eggs there is always an immediate 

 and almost instantaneous con- 

 sumption of oxygen by the eggs. 

 In the course of the first minute 

 the uptake of oxygen is many 

 times that of the same eggs one 

 minute before the addition of the 

 sperm, and more is usually taken 

 up in the first minute than is 

 taken up in the second, third, and 

 fourth minutes, after the addition 

 of the sperm, taken altogether. 



In all instances the C0 2 out- 

 put of the eggs follows the oxygen 

 uptake very closely, the respiratory 

 quotient being in the neighbour- 

 hood of 0-92. 



At standard barometric pres- 

 sure, and temperature of 14'5 C., 

 it was found that 4'06 mg. of egg 

 nitrogen ( million eggs) before 

 fertilisation consumed T5 cub. mrn. 

 of oxygen in ten minutes; after 

 fertilisation the same eggs con- 

 sumed 56 cub. mm. in this time ; 

 there was thus an increase in the 

 respiratory quotient of the eggs ten 

 minutes after fertilisation of some- 

 thing like thirty-seven times that 

 of the unfertilised condition. If 

 we consider the increase taking 



5 

 Minutes . 



FIG. 59. Chart showing the amount 

 of oxygen taken up, and the carbon 

 dioxide given off, in the first ten 

 minutes after the addition of the 

 sperm to the eggs of Echinus mic- 

 rotuberculatus , 56 cub. mm. of 

 oxygen being taken up by the 

 fertilised egg in this time, as com- 

 pared with 1'5 cub. mm. oxygen 

 consumed by the same eggs in the 

 unfertilised condition in the same 

 interval. 



Unbroken curve = oxygen ; broken 

 curve = carbon dioxide. 



Respiratory quotient, about 0*9. 

 Half a million eggs (4'06 mg. egg 

 nitrogen). Temp., 14'5 C. Bar. 

 760 mm. Hg. 



1 Shearer, "On the Oxidation Processes of the Echinoderm Egg during 

 Fertilisation," Proc. Roy. Soc. London, B., vol. xciii., 1922. 



