Wounded Plants . 
547 
CO. 
produced and of 0 2 absorbed shows that the ratio of 2 does 
not change to any very great extent after injury, always 
excepting the first two hours, concerning which an explanation 
has already been given. The average ratio with uninjured 
potatoes is almost -50, from which after the first sudden rise 
a second slower ascent is found, which corresponds to the 
curve of respiration as found in the Pfeffer-Pettenkofer 
apparatus. At the time of the greatest evolution of C 0 2 it is 
about 75 or *8o, falling again as the respiration decreases. 
In other words, somewhat more C 0 2 is given off in proportion 
to the 0 2 absorbed in the injured than in the uninjured 
condition. With the carrots experimented upon, even less 
change was found in three of the experiments (Expts. 40, 41, 
42) ; it remained almost the same, while in a fourth it was 
slightly lower. In the analyses of respiration from seedlings, 
in two cases there was at first a rise in the ratio to which 
it kept during the entire experiment (Expts. 44 and 46), 
while in one case there was an appreciable fall to an amount 
equalling the respiration in the uninjured condition (Expt. 45). 
In the case of leaves, those of Veronica speciosa showed a 
distinct increase of the ratio at the time when the respiratory 
activity is at its maximum. In no case was there observed 
such a marked increase of the amount of oxygen absorbed as 
is indicated by the results of Stich’s experiments. 
It is apparent that the amount of C 0 2 produced bears 
a close relationship to the amount of 0 2 absorbed, the latter 
always, with the one exception already noted, being in excess 
of the former, but to no very great extent. It will be noticed 
in the following table that the amount of oxygen absorbed 
after injury, over and above that theoretically required for the 
amount of C 0 2 produced, is somewhat more than in the 
uninjured condition, being at its highest when the respiration 
is strongest. It is, however, proportionally to the C 0 2 formed, 
far less than before injury. It may possibly be due to the fact 
that the processes, involving the absorption of oxygen, which go 
on in the plants under normal conditions are simply somewhat 
