638 



THE RESPIRATION AND 



[PT. Ill 



the male and female pronucleus takes place later on there is no fresh 

 rise in the process, but rather a further slowing down. This is illus- 

 trated by Fig. 1 1 o, which shows an experiment covering a longer 

 period. At the 25-minute point, where the nuclei fuse, there is no 

 kink in the curve, and the process is slowing off. "The nuclear 

 features of syngamy", as Shearer puts it, "seem connected in no 

 direct way with the oxidations taking place in the ovum," 



Such a conclusion is in agreement with the work of Warburg, which, 

 as we have already seen, led to the view that the surface of the egg 

 was of particular importance 

 with regard to the oxidations 

 proceeding in it, and hence the 

 respiratory rate. Injury to the 

 egg-membrane is invariably 

 followed by a great increase of 

 oxygen consumption of echino- 

 derm eggs, and, as will be noted 

 presently, Meyerhof found that 

 similar treatment was accom- 

 panied by a definite increase 

 in heat production. In eggs 

 treated with hypotonic sodium 

 chloride solutions, the absence 

 of calcium and potassium ions 

 interferes with the normal con- 

 dition of the cell- wall, and the 

 oxygen consumption rises to 

 five or six times the normal. In just the same way the heat 

 production rises from o-g to 3-4 gm. cal. per hour after treatment 

 with valerianic acid, which induces artificial membrane formation. 

 There is as yet no satisfactory explanation for these phenomena, for 

 the most recent knowledge which has accumulated about oxidation 

 processes can hardly allow us to be satisfied with the simple concep- 

 tion of an accumulation of iron in the surface layer of the egg, as 

 Warburg suggested. Even if it were there, and were released in some 

 way by parthenogenetic agents, it does not, as is now known, catalyse 

 all types of oxidation. However, Runnstrom's work has shown that 

 the rise in metabolic rate which occurs at fertilisation is connected 

 both with the colloidal state of the cell-interior and with the degree 

 of contact between the "Atmungsferment " and its substrates. 



