ACTION OF ANESTHETICS 117 



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

 of O-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 disappears and the leaves then evolve as 

 much carbon dioxide as in normal respiration. In medium 

 doses, 0-2 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 after 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. Following 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 adminis- 

 tration of a continuous dose of chloroform produces the same 

 effect as a single dose two or three times as strong. Thoday * 

 likewise found that in Prunus lanrocerasus, Helianthus tuberosus 

 and Tropceolum majus 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 is sufficiently large to effect a visible 

 disorganization, such as change in colour, f there is an initial 

 outburst of carbon dioxide then a fall to a very low level and 

 the absorption of oxygen no longer shows any co-ordination 

 with the amount of carbon dioxide evolved. The absorption 

 of oxygen in some way is connected with the cell contents, 

 especially tannin. In the Tropceolum leaf, which is free 

 from tannin, the absorption of oxygen is much lower than 

 the output of carbon dioxide, whereas in the cherry laurel 

 and the artichoke, both of which contain tannin, the initial 

 up-take of oxygen is very rapid, then it declines but 



* Thoday : "Ann. Bot.," 1913, 27, 697. 



f The change in colour is due to the oxidation of tannins and glucosides 

 by appropriate enzymes, oxidases for example (see Vol. I., p. 498). It may 

 be conveniently seen by exposing the flowers of the white lilac to the fumes 

 of phenol under a bell glass. 



