SECT. 4] HEAT-PRODUCTION OF THE EMBRYO 631 



rate in one case for monospermic eggs was 0-456 c.c. oxygen and 

 for polyspermic eggs was 0-498, a negligible difference. 



Warburg had been led to speculate on the part played by the 

 actual structure of the cells in metabolism by the fact that various 

 agents, especially pH, seemed to affect the respiratory intensity by 

 acting simply on the surface of the cells. He investigated, therefore, 

 the respiration of acetone preparations of staphylococci and yeast 

 cells, contributing the results in a joint paper with Meyerhof, who 

 investigated the eggs of Echinus miliaris. The oxygen consumption 

 of unfertilised eggs pounded up with sand was compared with that 

 of eggs normal and untreated. In the case of unfertilised eggs, the 

 oxygen consumption was not abolished altogether by this pulverisa- 

 tion, although it was definitely decreased. From 0-5 to 1-5 hours 

 after the treatment a half to two-thirds of the original respiratory rate 

 was found, but during the third hour this sank to between a quarter 

 and a third of the original value. Thus the intact eggs would have a 

 rate of 0-053 c.c. oxygen and the pulverised ones a rate of 0-033 ^.c. 

 In the case of the fertilised eggs, this fall after pulverisation was 

 rather more pronounced; as an example: 



Respiratory rate c.c. oxygen 

 per hour per 28 mgm. nitrogen 



Unfertilised 



2-cell stage 



4-ceIl stage 

 i6-cell stage 



But insufficient experiments were done with the fertihsed eggs to en- 

 able this point to be presented with certainty. These, it may be noted, 

 were the first respiration experiments in which manometric methods 

 were used as opposed to the Winkler titration which had previously 

 been universal. The acetone preparations were found to behave rather 

 like the egg-Breis, for, although the oxygen consumption was much 

 less than in the intact normal eggs, it was yet by no means absent. 

 The integrity of the cells was evidently only partially responsible 

 for the oxygen uptake of the original material^. In a later paper 

 Warburg pursued the question still further. He invented a method 

 of cytolysis in which echinoderm eggs were centrifuged rapidly and 

 shaken violently — egg-preparations according to this method not 

 only took up oxygen, but also gave off carbon dioxide. With this 



^ Cf. Penrose & Quastel's experiments with bacteria. 



