A THEORY OF INJURY AND RECOVERY. 



I. Experiments with Pure Salts. 



By W. J. v. OSTERHOUT. 

 {From the Laboratory of Plant Physiology, Harvard University, Cambridge) 



(Received for publication, September 14, 1920.) 



Previous researches^ indicate that the process of death conforms to 

 the laws of chemical dynamics and that further investigation of 

 this subject may throw light on the fundamental mechanism of nor- 

 mal life processes. The present series of papers continues these 

 studies and deals with the recovery of cells after exposure to toxic 

 solutions. 



When the marine alga Laminaria is transferred from sea water to 

 a solution of sodium chloride (of the same conductivity as the sea 

 water) its electrical resistance falls steadily until it reaches a sta- 

 tionary condition, which indicates death. If the tissue is replaced 

 in sea water before this point is reached we observe that the resistance 

 rises; this may be called recovery. In earlier stages of the death pro- 

 cess recovery may be complete {i.e. the normal resistance may be 

 regained) but this is not the case in the later stages. This is evident 

 from Fig. 1, which shows the death curve in a solution of NaCl and 

 recovery curves after various periods of exposure to the solution .^ 



If in place of sodium chloride we employ calcium chloride and vari- 

 ous mixtures of these salts, varying the times of exposure, and some- 

 times transferring the plant from one of these solutions to another, 

 instead of replacing it in sea water, a very complicated set of curves 

 is obtained. It is of interest to find that these may be predicted 



^Osterhout, W. J. V., Proc. Am. Phil. Sac, 1916, Iv, 533; /. Gen. Physiol., 

 1920-21, iii, 15. 



2 Cf. Osterhout, W. J. V., /. Gen. Physiol., 1920-21, iii, 15. The recovery curves 

 rise to definite levels at which they may remain for days under favorable con- 

 ditions. Often, however, there is a gradual decline which may be more rapid 

 than that of the control. 



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