634 



THE RESPIRATION AND 



[PT. Ill 



Henze admitted that after a certain point, as was shown later for 

 Dixippus morosus by v. Buddenbrock & v. Rohr, and for Fundulus 

 heteroclitus by Amberson, Mayerson & Scott, the oxygen utiHsation 

 ceased to follow oxygen partial pressure. Subsequent work with other 

 eggs has tended to confirm Henze rather than Warburg ; thus Dakin 

 & Dakin and Burfield have shown for the plaice's egg and Parnas & 

 Krasinska for the frog's egg that the respiratory rate depends directly 

 on the partial pressure of oxygen, below a certain point. Recently 

 Drastich, working with the eggs of Strongylocentrotus lividus, has shown 

 that there is a linear relation between cubic millimetres oxygen used 



Partial pressure of Oxygen 

 Fig. io6. 



50 TOO 



pressure of oxygen 



Fig. 107. 



per gram per hour and log. partial pressure. This would imply a 

 state of affairs in which the curve of oxygen consumption fell off 

 rapidly at low partial pressures (see Figs. 106 and 107). And Amber- 

 son finds no change in oxygen consumption of Arbacia eggs between 

 228 and 20 mm. partial pressure of oxygen, though below that it 

 falls off quickly. Everything seems to depend upon the level of 

 oxygen concentration at which this point comes; thus Loeb, in his 

 work on Ctenolabrus eggs, could find no difference in rate of develop- 

 ment or morphology between eggs in air or in 100 per cent, oxygen, 

 and Krogh & Johansen successfully hatched plaice eggs in oxygen 

 pressures of one-quarter the normal (230 mm. abs.). Below this point 

 abnormalities occurred. 



Warburg returned to the subject of normal respiration in 19 15, 



