162 RESPIRATION 



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 in anaerobic conditions much carbon 

 dioxide is produced and their life is prolonged. With regard 

 to alcohol, a similar correlation obtains ; in a specific in- 

 stance etiolated bean leaves in 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 in precisely similar conditions 782-4 mgs. of car- 

 bon dioxide and 724-6 mgs. of alcohol, a ratio of no : Q2-6.f 



Boysen- Jensen, J from his study on the relationship of the 

 alcohol produced in anaerobic respiration and the carbon 

 dioxide evolved in aerobic respiration, divides the higher 

 plants into two classes in which the ratio anaerobic alcohol/ 

 aerobic carbon dioxide is respectively > 0-35 and < 0-35. 

 To the first group belong most of the classical examples of 

 anaerobic respiration and to the second group those plants 

 which show a weak anaerobic respiration, such as potato tubers, 

 leaves of Tropceolum, seedlings of Sinapis alba, and fungi such 

 as Aspergillus and Penicillium. He selected alcohol for a 

 measure of anaerobiosis in that it has its origin in monosac- 

 charides, whilst the carbon dioxide produced in the absence of 

 oxygen may have diverse origins. 



In the lower plants this parallelism is not so obvious, thus 

 Kostytschev § found that mushrooms containing no sugar || 

 give origin to much carbon dioxide but no alcohol when 

 grown in anaerobic conditions, possibly because the alcohol 



* Palladin : " Rev. gen. Bot.," 1894, 6, 201. 



f Palladin and Kostyschev : " Abderhalden's Handbuch," 1910, 3, 



479- 



X Boysen-Jensen : " Kgl. Dansk. Videns. Selskab. Biol.," 1923, 4, 1. 



§ Kostytschev. : " Ber. deut. bot. Ges.," 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 in 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. 



