LIPOID-ALTERANT SUBSTANCES 205 



The relative effects of these compounds on the anaer- 

 obic growth of yeast were similar; the following solutions 

 produced about the same degree of inhibition : 



Methyl urethane 8% 



Ethyl urethane 4% 



Propyl urethane 2% 



Isobutyl urethane 1% 



Phenyl urethane o. 1% 



These results^ are similar to those of Regnard with 

 alcohols, cited above. 



Usui, working under Warburg's direction,^ found also 

 a decrease in the oxygen consumption of vertebrate 

 tissues (liver, central nervous system) under the influence 

 of narcotic compounds (alcohols, ketones, urethanes, 

 methyl urea, and phenyl urea) ; but in order to produce 

 marked depression of oxidations much higher concentra- 

 tions were required than in normal reversible narcosis, 

 and the effect was imperfectly reversible. This result 

 is interesting as indicating that anaesthesia is not neces- 

 sarily associated with a decrease of intracellular oxida- 

 tions, as Verworn and others have supposed; in fact, 

 Warburg, Winterstein, Loeb and Wasteneys, and others 

 have shown in a number of instances that anaesthesia 

 when perfectly reversible does not necessarily involve 

 a decrease in oxygen consumption.^ Diminished oxida- 

 tion is to be regarded rather as a secondary consequence 

 than as a cause of narcosis. Apparently the chemical 



I 



Warburg and Wiesel, loc. cit. 



^Usui, Arch. ges. Physiol., CXLVII (191 2), 100. 



3 Warburg, Z. physiol. Chem., LXVI (1910), 305; LXX (1911), 

 413; Winterstein, Biochem. Z., LXI (1914), 81; also Winterstein's 

 book on narcosis; Loeb and Wasteneys, Journal of Biological Chemistry, 

 XIV (1913), 517; Biochem. Zeitschrift, LVI (19 13), 295. 



