150 RESPIRATION 



made on their distribution and relation to the oxidative aspects 

 of respiration. 



Wieland * has drawn attention to observations by Lesser, f 

 Rywosch, J and Jorns § that anaerobes such as Bacillus tetanus 

 and B. botulinus are deficient in catalase whilst aerobic or- 

 ganisms such as Pneumococcus and Sarcina, and facultative 

 aerobes such as yeast contain catalase in quantity. It is 

 considered that the occurrence of catalase in those cells and 

 tissues which require oxygen is necessary for the twofold 

 purpose of preventing the accumulation of hydrogen peroxide 

 which is toxic to the cell, and for the liberation of oxygen. 

 Hydrogen peroxide is regarded as the first product of the 

 oxidation of hydrogen by oxygen which acts as the hydrogen 

 acceptor in the cell, 



2 + 2H = H,0 2 . 



The catalase then acts upon the resulting hydrogen peroxide, 

 breaking it up into water and oxygen, which latter is then 

 available for further oxidation, 



H 2 0„ = H 2 + O. 



This cycle of changes does not occur in anaerobic oxidations, 

 which may explain the absence of catalase in these conditions. 

 Appleman || found that the oxidase content of the expressed 

 juice of the potato is not indicative of the intensity of the 

 respiration of the tuber, whilst the catalase activity shows 

 a striking correlation. Similarly for sweet corn, in which in- 

 stance the respiration in the milk stage is high when first 

 collected but in storage rapidly decreases, the decrease being 

 accompanied by a nearly proportional fall in catalase activity. 

 In the pine-apple, Reed ^f found that oxidase and catalase 

 are independent ; the amount of the former remains constant 

 during ripening of the fruit whilst the catalase increases. In 

 the wheat and certain allied plants, the embryo shows a twenty- 

 eight to twenty-nine-fold greater catalase and oxidase activity 



* Wieland : " Ber. deut. chem. Gesclls.," 192 1, 54, [B], 2353. 



j Lesser : " Zeitsch. Biol.," 1906, 48, 1. 



i Eywosch : " Zentr. Bact.," 1907, 44, 295. 



§ Jorns : " Archiv. d. Hyg.," 1908, 67, 134. 



|| Appleman : " Amer. Journ. Bot.," 1910, 3, 223 ; 1918, 5, 207. 



1j Reed : " Bot. Gaz.," 1916, 62, 409. 



