128 RESPIRATION 



20° to 21° C. and gives the ratio of the carbon dioxide evolved 

 per hour to the amount of protein unacted upon by pepsin : — 



Age of Seedling COj 



in Days. ~N~ ' 



4 ........ 106 



6 . . . . . . . i 05 



7 1-18 



9 115 



Palladin found a similar ratio to obtain in other plants, 

 the following being some of the values obtained : — 



Wheat seedlings .... 1-05, 1-15, 1-07, i-iS 



Lupin seedlings .... 1-12 



Etiolated leaves of the broad bean after 



cultivation on sugar solution . i-io 



The differences between these observed ratios are not 

 considered to be significant by Palladin in view of the experi- 

 mental difficulties. From his observations he draws the 

 general conclusion that for a given temperature and with an 

 adequate amount of carbohydrate, the relation between the 

 quantity of carbon dioxide evolved by different plants in one 

 hour and the quantity of protein unacted upon by gastric 

 secretion, in vitro, is a constant. For a temperature of 19 

 to 20 C, C0 2 /N 2 == i-i. 



The amount of the protein referred to, as Kidd, West and 

 Briggs have pointed out, is a measure of the amount of respiring 

 cell matter. 



With regard to the fats, there is but little precise infor- 

 mation available from the point of view of respiration. Their 

 conversion to carbohydrate may be one phase of the involved 

 problems, and necessitates a much greater up-take of oxygen 

 where fats are the predominating respirable material as com- 

 pared with those in which carbohydrate is the prime respirable 

 substance, that is, the respiratory quotient of a fat-containing 

 seed is of a comparatively low value. To what extent the 

 products of the hydrolysis of fats are immediately respirable, 

 is another aspect of the subject awaiting investigation. 



The observed differences in the respiratory activity is 

 sometimes ascribed to the difference in the quantity of the 

 material available for physiological combustion. According 



