

STIMULATION 79 



and affects the CO 2 /O 2 ratio which generally is greater in 

 pollinated carpels as compared with unpollinated gynaecia. 

 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. 



THE ACTION OF ANAESTHETICS. 



The action of anaesthetics on the output of carbon dioxide 

 is partly stimulatory and partly narcotic. Irving f found that 

 the effect of a single dose depended on its strength : a dose of 

 I c.c. of chloroform in 970 c.c. of air brings about an immediate 

 rise in the output of carbon dioxide, this effect subsequently dis- 

 appears and the leaves then evolve as much carbon dioxide as 

 in normal respiration. In medium doses, -2 c.c. of chloroform in 

 970 c.c. of air, there obtains the same initial outburst of carbon 

 dioxide which falls away more quickly than in the case of a 

 small single dose and for a time remains below normal ; after 

 about six hours recovery is complete and the evolution of carbon 

 dioxide is normal. With a dose of I c.c. of chloroform in 970 

 c.c. of air, the initial outburst of carbon dioxide is earlier and 

 its curve is steeper, the production of carbon dioxide slowly 

 diminishes and there is no recovery. After a strong dose of 

 chloroform, 10 c.c. in 970 c.c. of air, there is no detectable 

 initial outburst and the carbon dioxide output quickly falls to 

 zero. The administration of a continuous dose of chloroform 

 produces the same effect as a single dose two or three times as 

 strong. ThodayJ likewise found that in the instances of 

 Prunus laurocerasus, Helianthus tuberosus and Trop&olum 

 ma/us that a small dose of chloroform leads to an immediate 

 stimulation of respiration, the evolution of carbon dioxide and 

 the absorption of oxygen increasing in like proportion, which 

 indicates that the two are co-ordinated. If, however, the dose 



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

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

 JThoday : Id., 1913, 27, 697. 



