THE PROCESS OF EXCITATION 109 



as can be observed in plants and certain invertebrate animals, 

 indicates that here also there is the possibility of another expla- 

 nation of these facts. Various attempts have been made to solve 

 the problem if reserve oxygen is present in the cell or not. The 

 experiments of Rosenthal^ carried out with his respiration calo- 

 rimeter, seemed to point directly to an oxygen reserve in the 

 organism of the mammal. He observed that during respiration in 

 an atmosphere rich in oxygen the respiratory quotient (CO 2 : O 2 ) 

 became lower than in ordinary air, that is, that oxygen, and that 

 indeed in considerable quantity, must be retained in the organism. 

 Nevertheless Falloise 2 found that when rabbits, which had been 

 kept in an atmosphere containing 80 per cent of oxygen, were 

 asphyxiated, the time necessary to produce death was no longer 

 than in animals which had been kept previously in ordinary air. 

 The correctness of the observations of Rosenthal have been dis- 

 puted by Durig. 3 Winterstein* also, employing the microrespira- 

 tion methods of Thunberg upon the spinal cord of the frog, 

 believed that he had found proof that an oxygen reserve cannot 

 take place. He reasoned thus : If the cells of the spinal cord 

 contain reserve oxygen, which is used up when pure nitrogen only 

 is breathed, then it necessarily follows that after reintroduction 

 of oxygen, following asphyxiation, a definite quantity must be 

 stored up again as reserve. In consequence, the respiratory 

 quotient following the intake of oxygen after asphyxiation should 

 be smaller than when the animal is in air. He found, however, 

 that the respiratory quotient does not essentially change and con- 

 cluded from this that storage of oxygen does not take place. 

 In these experiments, however, there exists no certain indicator 

 as to the state of the spinal cord during asphyxiation and recovery 

 in the given case. The spinal cord may be severely injured and 



1 Rosenthal: "Untersuchungen iiber den respiratorischen Stoffwechsel." Arch. f. 

 Anat. u. Physiologic physiolog. Abt. 1902 und Suppl. 1902. 



2 Falloise: "Influence de la respiration d'une atmosphere suroxygene sur 1'absorp- 

 tion d'oxygene." Traveaux du laborat. de physiol. de L. Frederic Liege, T. VI. 



3 Durig: "Ueber Aufnahme und Verbrauch von Sauerstoff bei Aenderung seines 

 Partialdruckes in der Alveolarluft." Arch. f. Anat. u. Physiol. physiol. Abt. 1903 

 Suppl. 



4 Winterstein: "Ueber den Mechanismus der Gewebeatmung." Zeitschr. f. allgem. 

 Physiol. Bd. VI, 1907. 



