n6 RESPIRATION 



is greater in pollinated carpels as compared with unpollinated 

 gynsecia. The most striking instance was afforded by the 

 Pelargonium, the pollinated carpels of which evolved from five 

 to eight times as much carbon dioxide as the unpollinated. 



Mention also may be made of Schley's * observations, who 

 found that the respiration of a geotropically stimulated root 

 is greater than that of an unstimulated root, the respiration 

 rate of the convex side being greater than that of the concave 

 side during the period of perception and response. 



Products of the plant's own metabolism may stimulate 

 its respiration. Thus Spoehr and McGee f observed that 

 when detached leaves of the sunflower and the bean were 

 grown in a nutrient solution containing sugar and amino acid, 

 the rate of respiration increased with that of the amino acid 

 in the culture medium even when the leaves contained supplies 

 of carbohydrate. When grown in darkness, when carbohy- 

 drate decreases and amino acid increases, there is a like 

 stimulation which tends to maintain a relatively higher rate 

 of respiration. From such observations they conclude that 

 carbohydrate alone does not determine the intensity of res- 

 piration, but that there is an accessory stimulating factor, 

 amino acid, in the plants examined. On the other hand, 

 Hafenrichter % concludes that in the soy bean grown in 

 darkness, the accumulation of amino acids is incidental 

 rather than necessary to respiration ; he obtained no evidence 

 that amino acids stimulate respiration. 



Although vegetable pathology is without our present 

 province, mention may be made of the fact that, as in the 

 animal, disease is frequently marked by an increased respira- 

 tion intensity. § 



THE ACTION OF AN/ESTHETICS. 

 The action of anaesthetics on the output of carbon dioxide 

 is partly stimulatory and partly narcotic. Irving || found that 



* Schley : " Bot. Gaz.," 1920, 70, 69. 



f Spoehr and McGee : " Carnegie Inst. Wash.," No. 325, 1923. 

 I Hafenrichter : " Bot. Gaz.," 1928, 85, 271. 



§ See, for example, Weimer and Harter : " Journ. Agric. Res.," 1921, 

 31, 627. Davis: " Bot. Gaz.," 1926, 81, 323. 

 || Irving : " Ann. Bot.," 1911, 25, 1077. 



