STUDIES IN PLANT -RESPIRATION AND PHOTOSYNTHESIS. 81 



carbohydrate-content, i. e., in which the respiratory energy release 

 is very low, can stand the absence of oxygen less easily than can 

 leaves with higher carbohydrate-content. Also, an anaerobic form 

 of respiration, in which the course of the reaction is different and the 

 energy of release quite low, does not suffice. 



In harmony with the conception of the dependence of photo- 

 synthesis on respiration are the observations of the effects of anes- 

 thetics or narcotics on photosynthesis. Claude Bernard discovered 

 the inhibiting effect on photosynthesis of chloroform, and this fact 

 has been repeatedly confirmed. ^ In fact, photosynthesis is far more 

 sensitive to the action of chloroform and ether than is respiration, 

 so that amounts of these anesthetics, which hardly affect the rate 

 of CO2 emission, exert a decidedly inhibiting effect on photosynthesis, 

 and with higher concentrations the capability for photosynthetic 

 work is entirely lost. Willstaetter and Stoll- have shown that in 

 leaves which have lost their photosynthetic power the four chloro- 

 phyll components are unchanged. Unfortunately, we have not been 

 able to gather sufficient data on the nature of carbohydrate metabo- 

 lism in leaves during narcosis to show definitely how the energy 

 release is affected. It would be using very unreliable evidence to 

 draw conclusions as to this point from the tropic and general move- 

 ment phenomena or other responses of plants under the influence of 

 narcotics. 



The Very interesting experiments of Pelster' bear directly on the 

 relation of photosynthesis and respiration. He found that while 

 photosynthesis is much lower in the varieties of the same species 

 containing Uttle chlorophyll, there is no direct ratio between photo- 

 synthetic activity and chlorophyll-content. Furthermore, the fight- 

 green or aurea varieties, with low chlorophyll-content, also have a 

 low respiratory activity as compared with the normal varieties. 

 However, here also there is no direct relation between respiration 

 and chlorophyll-content. But Pelster's results seem to show a 

 relation between respiratory and photosynthetic activity. The 

 quotient of the respiration and photosynthesis values of the light- 

 green types are: Ptelea 84.1/47.5 = 1.77, Catalpa 58.8/34.2 = 1.72, 

 Mirabilis = 2.0, Ulmus = 2.0, Populus = 2.1, while Atiflex showed 

 the very low quotient 1.3. 



The findings of Pelster can be explained, of course, in a large 

 measure also, on the ground that due to the low photosynthetic 



1 Bernard, Cl. Lecons sur les phfenom^nea de la vie, 278 (1878). 



Irving, A. A. Ann. of Bot., 25, 1077-1099 (1911). 



Kegel, W. Inaug. Diss., Goettingen (1905). 



EwART, A. J. Jour. Linnean Soc, 31, 439 (1895). 



Bonnier, G., and L. Magin. Ann. d. Sci. Nat. Bot.. (7), 3, 14 (1886). 

 s Willstaetter, R., and A. Stoll. I. c, 39. 

 • Pelster, W. Beitrdge zur Biologic der Pflamen, 11, 249-304 (1912). 



