RESPIRA TION 



607 



oxidation in the cell. Further, a somewhat larger amount of carbon dioxide is 

 dissolved or combined as bicarbonate. In our description of Fletcher's experiments 

 (page 443), we have seen that the carbon dioxide given off by muscle in nitrogen 

 is not greater than can be accounted for in the way mentioned. In absence of 

 oxygen, therefore, no combustion process goes on in muscle ; in other words, there 

 is no oxygen present in a form available for oxidation. Further experiments on 

 the disengagement of carbon dioxide from muscle by heat, the results of which are 

 incapable of explanation on the theory of intra-molecular oxygen, will be found in 

 the paper by Fletcher and Brown (1914). Similar conclusions were drawn by 

 Verzar (1912, 3, p. 47) with regard to the muscle of warm-blooded animals. He 

 found that there is no oxygen tension in this tissue. If there is no oxygen tension, 

 there can be no oxygen that it is possible to use for oxidation purposes in the 



\ 



FIG. 189. WINTERSTEIN'S MICRO-RESPIRATION APPARATUS. With tubes for introduction of 

 various gases. To be used also for analysis of gases in small quantities of blood. 



cell. There is none that can be dissociated, either for combustion of another part 

 of the " giant " molecule or for that of other molecules. If there is any store, it 

 is in stable combination and does not concern us here. Peters (1913, p. 266) states 

 that his experiments do not absolutely decide the question, but he could obtain no 

 evidence in favour of a storage of oxygen. 



Turning to other tissues, the experiments of Winterstein (1907) on the spinal 

 cord of the frog may be referred to. The micro-respirometer of Thunberg (1905, 1) 

 was used. This apparatus is similar to that represented in Fig. 189, which is the 

 form given to the instrument by Winterstein in order to use it for the estimation 

 of the gases in blood, as well as for respiratory experiments. Into this apparatus 

 the isolated spinal cord of the frog, prepared by Baglioni's method (1904), was 

 introduced. ' In oxygen it remains excitable for forty-eight hours, in nitrogen 

 only for half an hour. The oxygen consumption at 16 to 18 is 268 to 300 c.mm. 

 per gram. The respiratory quotient is less than unity, hence some substance other 



