540 
R ic hards. — The R esp ira tio n of 
more precisely from twenty-four to thirty hours, after the 
injury has been inflicted, provided that the healing of the 
wound has been in no way retarded otherwise than by 
keeping the plants in a moist atmosphere. The course of 
this curve is fairly constant, and a decrease to a nearly normal 
rate of respiration, although much more gradual than the 
increase, is to be expected in from seven to eight days. In 
the case of the potatoes experimented with, the respiration 
never reaches quite so low a point as the normal, but this 
amount is in the first place so exceedingly small that hardly 
anything else could be expected when taking into considera- 
tion the increase of temperature and moisture to which the 
specimens were subjected. The amount of C 0 2 evolved in 
comparison to the normal production is somewhat variable, 
but it will be noticed that it usually corresponds to about 
twice the amount found at the time when the plant is at its 
lowest respiratory condition after injury. 
In potatoes the percentage increase of the respiration of 
the injured over the uninjured condition is far greater than in 
any other of the plants examined. It was with potato- 
tubers that Boehm 1 first observed the phenomena attending 
injury, and he also records a maximum on the second day, 
but in one instance only. Stich 2 in two cases gives a 
maximum at a somewhat earlier period, but that is a point 
which might readily vary with the conditions of the experi- 
ment. With carrots the maximum period (Expts. 14 and 15) 
was found not to be reached in some cases until the beginning 
of the third day. The first strong evolution of C 0 2 during 
the first few hours is very well marked in carrots (Expts. 14 
and 15), and is almost as great as the maximum reached 
later. In the same way sugar-beets and the ordinary red 
beet showed a similar respiration-curve after injury, although, 
weight for weight, the evolution of C 0 2 is by no means so 
CO, 
great as with carrots. As regards the - equation, it will 
be seen in general that, although between the uninjured and 
1 Bot. Zeit., Bd. xlv, p. 671, 1887. 2 1. c., p. 53, Versuche, 11 and 12. 
