194 EXPERIMENT STATION RECORD. 



to a vaciiuin Cor a considerable time, ImU wilt, turn yellow, and take on 

 a peeiiliar odor indicative of a changed condition of tlieir tissues. 



The absorption of oxygen is influenced in the same way as has been 

 shown for the liberation of carbon dioxid. 



The respiration of green and etiolated leaves, W. Palladin 

 [Mitt. Vnir. (Jharhnc, pp. ;J1; <(hs. in Hot. CeiifhI., 08 {1894), No. il^pp. 

 375-377). — ISTunierous experiments were made with leaves of Viciafaha 

 by the Pettenkofer method for estimation of the CO-, in the respiration 

 of green and etiolated leaves. 



Freshly cut leaves showed a very low respiration, which the author 

 thinks is due to the low carbohydrate content of the leaves. If both 

 green and etiolated leaves be placed for some time in a cane-sugar solu- 

 tion they will take up a considerable amount of the carbohydrates, 

 which will be shown almost immediately by the increased respiration 

 of the leaves. However, if they are placed in distilled water a corre- 

 sponding loss will be noticed. This seems to be a demonstration of 

 the effect of the carbohydrate content of leaves on their respiration. 



The author established as the unit of respiration intensity the amount 

 of carbon dioxid given off in 1 hour for each 10 gm. of albuminoid 

 substance in the leaf. The amount of albuminoids was estimated from 

 the dry subvStance, and the freshly cut leaves were found to have a con- 

 stant percentage of albuminoids in their dry substance, it being 44.6 

 per cent for etiolated and 38.7 f(n^ green leaves of Vicia faba. Based 

 on this proportion, the average of 4 experiments gave as the respira- 

 tion intensity of etiolated leaves 169.3 mg., and of 2 experiments for 

 the green ones 163.3 mg., showing that the respiration intensity is pro- 

 portionate to the carbohydrate content of each. 



The increased respiration of leaves as a consequence of their having 

 been placed for some time in a sugar solution might be attributed to 

 the action of some fungi or bacteria, but this the author showed could 

 not be the case by keeping leaves for a long time in the solution and 

 estimating their respiration from time to time. The amount was found 

 to be nearly constant instead of increasing, as would be the case if 

 due to bacteria or fungi. 



With lupines and wheat the relation between the CO2 given oft" and 

 the albuminoid content of leaves was not determined. The relation as 

 shown by the intensity of the respiration of green and etiolated leaves 

 of wheat is not always constant. The author considers, as shown by his 

 experiments with wheat, that etiolated leaves of stemless plants, as a 

 result of their being richer in glucose, have a greater respiration than 

 stalked plants. 



The respiration coefficient (CO2: O2) in the etiolated leaves of Vicia 

 faha is between 0.72 and 0.76 when kept in the sugar solution. If kept 

 in distilled water it falls to 0.63 to 0.65. The corresponding figures for 

 green leaves are not given. 



