254 IRRITABILITY 



oxydative processes would indeed be out of the question in such 

 a view. 



The assumption, however, that in a living system at the same 

 moment when oxygen is removed from the neighborhood, let us 

 say by a stream of nitrogen, no oxygen would be present and 

 that in consequence every oxydative process must cease, contains 

 so little probability that I have rejected it on various occasions. 1 

 The way in which irritability is lost in asphyxiation of the nerve 

 likewise very clearly demonstrates the untenability of this view. 

 The recent investigations of Lodholz 2 have shown that decrease of 

 irritability takes place after a sudden displacement of all oxygen 

 from the surrounding medium uniformly and gradually in the 

 form of a logarithmic curve. If at the moment of oxygen with- 

 drawal from the outer medium, metabolism became entirely 

 anoxydative, the curve of irritability must under all circumstances 

 show a sudden steep decline at this point, and subsequent to this 

 a further slozver decrease. For, as the oxydative processes con- 

 stitute by far the chief part in the energy production of living 

 substance, the production of energy, and with this irritability, 

 would undergo considerable loss at the same moment in which 

 oxydative was replaced by anoxydative disintegration. The curve 

 of decrease of irritability during the transition period from 

 oxygen supply to oxygen withdrawal shows, on the contrary, a 

 completely uniform course and it is not until later that a very 

 slow decline takes place, which only after a prolonged time as- 

 sumes increasing rapidity. But the assumption that *at the 

 moment when the supply of oxygen ceases, anoxydative breaking 

 down could acquire such enormous dimensions that it furnishes 

 just exactly the same amount of energy as was before supplied 

 oxydatively, is a view which no one will seriously entertain. In 

 connection with this I wish to call attention to the experiments 

 of Frohlich 3 in which he compared the time required for asphyx- 

 iation to take place in the nerves, when, on the one hand, the frogs 

 had been kept several days previous to the experiment in tempera- 



1 Compare lecture V; lecture VII. 



2 The investigations have not yet been published. 



3 Fr. W. Frohlich: "Das Sauerstoffbedurfniss des Nerven." Zeitschr. f. allgem. 

 Physiol. Bd. Ill, 1904. 



