OXYGEN REQUIREMENT OF NERVOUS TISSUE 575 



that a muscle rendered incapable of excitation by some 

 poison continues to show a not inconsiderable capacity for 

 taking up oxygen. According to Verzar the quantity of 

 acid entering into the blood in connection with muscular 

 contraction is sufficient to reduce the affinity of the haemo- 

 globin for oxygen. The fact that for a considerable time 

 after the expiration of a contraction muscle shows an in- 

 crease in its oxygen consumption is significant of the im- 

 portance of oxygen in the process of its recovery. 43 System- 

 atic studies of the gas interchange of the smooth muscle 

 of the stomach and intestine have been made by 0. Cohn- 

 heim by his method. 44 



Numerous studies have been made of the gas exchange 

 of the heart. They are largely devoted to comparison of 

 the cardiac muscle with the skeletal muscles, the relation 

 of gas interchange with the rhythm and mechanical actions, 

 the influence of vagus stimulation and of various poisons 

 (as calcium chloride, chloroform, alcohol, digitalin, adren- 

 in, etc.). The method of perfusing the surviving heart of a 

 warm-blooded animal with blood which Bohde has carefully 

 worked out in E. Gottlieb's laboratory promises important 

 results in combination with the modern methods of blood 

 gas analysis. 45 



Oxygen Requirement of Nervous Tissue. The respira- 

 tory processes of the nervous system have been studied 

 particularly by Hill and Nabarro, F. W. Frolich 46 (in Ver- 

 worn's laboratory) and by H. Winterstein. 47 Frolich be- 

 lieves that on augmentation of their oxygen allowance the 

 excitability of nerves is increased up to a certain degree, 



*F. Verzdr (Physiol. Lab., Cambridge), Jour, of Physiol., 44, 253, 1912; 

 cf. also G. C. Mathison, Jour, of Physiol., 43, 347, 1911. 



44 0. Cohnheim, Zeitschr. f. physiol. Chem, 54, 461, 1908; 0. Cohnheim and 

 D. Pletnew, Zeitschr. f. physiol. Chem., 69, 102, 1910. 



^Yeo, W. E. Dixon (Cambridge), Brodie and Cullis, Locke and Rosen- 

 heim, G. D. Cristina (Naples), Arch. di. Fisiol., 5, 347, 1908; E. Rohde (R. 

 Gottlieb's Lab., Heidelberg), Arch. f. exper. Pathol., 68, 401, 1912. 



46 F. W. Frolich (Verworn's Lab., Gottingen), Zeitschr. f. allgem. Physiol., 

 5, 131, 1903. 



"H. Winterstein (Rostock), Zeitschr. f. allgem. Physiol., 6, 315, 1906. 



