Wounded Plants . 
549 
General Considerations. 
Considering the increased respiration attending the injury 
of plants as an indication of stimulated activity on the part 
of the tissues, its significance is understood at once. In 
common with the general tendency of living organisms, plants 
endeavour to tide over the critical period following an injury 
by exerting an unusual effort to overcome the same. If the 
unfavourable conditions be too severe or too long-continued, 
death, will naturally result ; but until vitality is so far weakened 
that even ordinary activity is diminished, or until the crisis is 
past and recovery assured, evidences of an acceleration of the 
ordinary functions of life will pretty surely be found in almost 
any living organism. In the case of plants, so far as the kind 
of injuries produced by cutting are concerned, a far greater 
amount can be suffered without fatal effects than in even 
fairly lowly organized animals, so that a direct comparison 
between the two is not to be instituted. Nevertheless, even in 
such organs as leaves, where death of the parts follows 
comparatively rapidly on any severe injury, a distinct increase 
in the rate of respiration was found. But it is not necessary 
to be limited to only this type of abnormal conditions, for 
numerous authors have shown that plants respond by increased 
respiration, and hence, it is to be understood, increased activity 
in general, to other unnatural conditions. Elfving 1 , experi- 
menting with various plants under the influence of chloroform 
and ether, found that respiration was very considerably acceler- 
ated, although he did not determine the curve from the point 
of view of time. Johannsen’s 2 work on the influence of an 
increased pressure of oxygen on seedlings shows a similar 
result even more plainly. He found that at first in almost 
every case the respiration was increased, falling again until 
finally death ensued. As has already been referred to, Stich 3 
1 Ofversigt af Finska Vetensk.-Soc.’s Forh., Bd. xxviii, 1886. 
2 Untersuch. aus dem Bot. Inst, zu Tubingen, Bd. i, 716, 1885. 
3 1. c. 
