110 IRRITABILITY 



even undergo degeneration during asphyxiation, and the recovery 

 following the reintroduction of oxygen may be either incomplete 

 or nil, without there being a method for its determination. Apart 

 from this. Lesser'- has already emphasized, in opposition to these 

 experiments, that the respiratory quotient in recovery is no crite- 

 rion to guide us. It is immaterial whether during asphyxiation 

 oxygen respiration occurs following a reserve supply, or that 

 an anoxydative formation of carbon dioxide has taken place, 

 for in both instances the respiratory quotient would be less after 

 asphyxiation when there is again an oxygen supply. It is, there- 

 fore, quite impossible to decide the question by the employment 

 of this method. For this reason Lesser has attempted to solve 

 the problem by means of quite another method, and was con- 

 vinced that he had refuted finally the belief in the existence of 

 reserve oxygen. His method consists in the employment of the 

 Bunsen ice calorimeter, by which he determines the heat pro- 

 duction of frogs, kept first in air, then in nitrogen, and at the 

 end of each experiment ascertaining the amount of output of 

 carbon dioxide, respectively in air and nitrogen. He found that 

 the quantity of heat, calculated in terms of 100 grms. body 

 weight per hour, produced in nitrogen was considerably less than 

 that under corresponding conditions in air, but that the produc- 

 tion of carbon dioxide, on the other hand, during the first hours in 

 nitrogen was doubled in amount, as compared to that in air. 

 From this he concludes that the carbon dioxide formation in 

 nitrogen must be different from that in air, as it is associated 

 with a reduced heat production. In other words, carbon dioxide 

 formation, while the animal is in a nitrogen atmosphere, does not 

 have its origin in oxydative processes at the cost of stored up 

 oxygen. I regret that I am unable to accept these arguments as 

 conclusive evidence against the assumption of an oxygen re- 

 serve, as this question cannot be decided by the use of such 

 methods. Lesser does not measure the amount of carbon dioxide 

 until the end of his experiments, that is, he learns merely the 



1 Lesser: "Die Warmeabgabe der Frosche in Luft und sauerstofffreien Medien. 

 Ein experimenteller Beweis dass die COj Production der Frosche im sauerstofffreien 

 Raum nicht auf Kosten gespeicherten SauerstofTs geschieht." Zeitschr. f. Biologie 

 Bd. 51, 1908. 



