MECHANISM OF RESPIRATION 165 



in respiration followed by a smooth decline to zero ; at the 

 death point the evolution of carbon dioxide was not markedly 

 smaller, and it may be considerably greater, than the normal 

 rate in living tissue. But this post-mortem respiration is 

 not shown in all instances. Palladin observed that the evolu- 

 tion of carbon dioxide from finely ground wheat is less than 

 from the living intact grains. 



He also made a comparative study of the effects of various 

 poisons on the evolution of carbon dioxide from living and 

 dead tissues : quinine hydrochloride in a -09 per cent, solution 

 gave a threefold increase in the output of carbon dioxide from 

 living stem apices of the broad bean, but was without effect 

 on killed apices ; a dose of 1 per cent, gave the same increased 

 yield from the live stems and reduced the evolution of carbon 

 dioxide from the dead. Arbutin in a I to 2 per cent, solution 

 depressed the respiration of wheat seedlings to a greater degree 

 in dead than in live seedlings. 



Quastel* remarks on the fact that if a suspension of Bacillus 

 coli be shaken up with toluol or with ether, the organism is 

 no longer capable of reproduction ; it is, in ordinary parlance, 

 dead ; but it can still activate formic, lactic and succinic 

 acids and this at rates not markedly divergent from those 

 due to the untreated organism. 



The parallelism between alcoholic fermentation and anae- 

 robic respiration is so close that the common opinion is that in 

 the ordinary plant the first phase of respiration is anaerobic. 

 As has been described elsewhere, f the precise sequence of 

 events in alcoholic fermentation is a matter of opinion, but of 

 the end products, alcohol and carbon dioxide, there is no doubt. 

 The carbon dioxide evolved in respiration has its origin in 

 this anaerobic phase by the action of carboxylase upon the 

 carboxyl groups, produced in the disruption of the sugar. 

 If oxygen be withheld, the non-gaseous products of the an- 

 aerobic phase will accumulate and ultimately kill the plant 

 if it be a typical aerobe. The second phase is aerobic and is 

 concerned with the oxidation of the products of anaerobiosis. 



* Quastel: "J. Hgyiene," 1928, 28, 139. 

 t See Vol. I., p. 489. 



