THE BIOLOGY OF THE CELL SURFACE 



ings on oxygen-consumption by the eggs of a sea-urchin 

 during the first minute after their insemination. Says 

 Shearer: "On addition of the sperm to the eggs there is an 

 immediate consumption of oxygen. 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 and third minutes after the addition 

 of the sperm taken together." Shearer thinks that this 

 "great initial inrush of oxygen into the egg and a corre- 

 sponding output of CO2 within the first minute after the 

 addition of the sperm" make it clear "that the sperma- 

 tozoon sets up an instantaneous oxidation-process in the 

 egg, which is unparalleled in the reactions of the animal-cell 

 for its sudden character." 



This period of a great initial inrush of oxygen established 

 by Shearer's findings coincides with the period of surface 

 changes described above during which time also the egg is 

 so susceptible to the action of dilute sea-water. During 

 this period the colloids in the ectoplasm go into solution, 

 material is destroyed. It is this solution at the sur- 

 face of the egg that is accompanied by the great rise in 

 oxygen-consumption. 



Shearer has also investigated heat-production in fer- 

 tilized eggs of sea-urchins. Rogers and Cole,^ using meth- 

 ods of higher precision, have reported findings on the 

 heat-production by the eggs of the sea-urchin, Arhacia. 

 Their results on the heat-production immediately following 

 insemination are of most interest to us. These workers 

 find that the rate of heat-production at the instant of 

 insemination is ten to twelve times that of the unfertilized 

 egg. Thereafter the rate of heat-production falls con- 

 stantly for twenty minutes to 65 per cent, of the value at 



^ Rogers and Cole, 192^. 



114 



