ANAEROBIC RESPIRATION 101 



amount of carbohydrate available for reduction in the plant 

 and on the experimental conditions employed.* 



Thus the amount of carbon dioxide evolved from etiolated 

 bean leaves, in an atmosphere free from oxygen, is negligible, 

 but if kept with their petioles immersed in a solution of sugar 

 for some time previous to their being placed under anaerobic 

 conditions much carbon dioxide is produced and their life is 

 more prolonged. With regard to alcohol, a similar correlation 

 obtains ; in a specific instance etiolated bean leaves under 

 anaerobic conditions gave 256-8 mgs. carbon dioxide and 68-3 

 mgs. of alcohol in thirty hours, a ratio of 100 : 26-5, whereas 

 leaves previously given sugar yielded under precisely similar 

 conditions 782-4 mgs. of carbon dioxide and 724-6 mgs. of 

 alcohol a ratio of 1 10 : 92 -6. f 



Whether zymase and carboxylase are of general occur- 

 rence in all those normally aerobic plants or members of 

 plants which are capable of living for a time under anaerobic 

 conditions remains to be discovered. 



This survey, brief though it be, is sufficient to indicate the 

 close connexion between, if not the identity of, anaerobic 

 respiration and fermentation. Amongst the lower plants 

 studied, this parallelism is not so obvious, thus Kostytschev J 

 found that mushrooms containing no sugar give origin to 

 much carbon dioxide but no alcohol when grown under an- 

 aerobic conditions, possibly because the alcohol is oxidized 

 almost as soon as it is formed : but however this may be, 

 more information is necessary before an adequate attempt can 

 be made to correlate the catabolic processes of these and like 

 plants possessed of such plastic metabolic methods. 



Reference may now be made to Palladin's ideas on respira- 

 tory processes. With regard to the origin of carbon dioxide, 

 he considers that there are three possible sources : that arising 

 from the activity of enzymes more or less closely associated 



* Palladia : Rev. gn. Bot.," 1894, 6, 201. 



t Palladin and Kostytschev : " Abderhalden's Handbuch," 1910, 3, 479. 



Kostytschev : " Ber. deut. hot. Gesells.," 1908, 25, 188 ; 26a, 1674 ; " Zeit. 

 physiol. Chem.," 1910, 65, 350. 



Glucose has been described as occurring in the mushroom and allied plants. 

 The amount varies greatly, according to the conditions under which the plants 

 are grown, and varies, not only in different batches, but also in individual plants 

 of one batch. These fungi also contain carbohydrates capable of yielding 

 sugars. 



