THE METABOLISM OF EGGS, I 63 



increase in the level of O2 uptake, fertilization is followed by a 

 transient increase in respiration, even though rate curves tend to 

 over-emphasize such effects. According to Boyd (1928), the same 

 thing happens in the eggs of Fundulus heteroclitus, though the time 



V) 



§ 



10 



o 



10 



o 



10 



20 



30 



40 



50 



60 



t (min.J 



FIG. 13. — Total CO2 production and O2 uptake in lA gas/hour, before and after 

 fertilization of eggs of Psammechinus miliaris. F, addition of spermatozoa. 

 Warburg indirect method. Gas phase, 03% CO2 in Oj. T° C, 20. (Laser 

 & Rothschild, 1939). 



scale is longer. Whether this always occurs and what its signifi- 

 cance is are questions which require further investigation. 



Respiratory quotient. After straightforward measurements of 

 O2 uptake, the next stage in a metabolic investigation often takes 

 the form of an examination of the respiratory quotient (R.Q.), i.e. 



