CHAPTER III 

 INJURY AND BECOVERY 



An investigation of the process of death leads us 

 naturally to a study of the power of the organism to 

 recover from exposure to unfavorable influences. 



An interesting aspect of this subject is the connection 

 between injury and permeability. In the opinion of some 

 writers permeability is a relatively fixed property of the 

 cell which changes only as the result of injury, and is then 

 altered^ irreversibly, while others assume that reversible 

 changes in permeability may form a normal part of the 

 activities of the cell.^ In view of the fact that such 

 changes may control metabolism it seemed desirable to 

 the writer to investigate them by determining conduc- 

 tivity, since (as will be shown in Chapter VI) an increase 

 in conductivity indicates an increase in permeability, and 

 since it is also possible to calculate the increase in proto- 

 plasmic conductivity (and hence of permeability) as dis- 

 tinguished from the increase in the conductivity of the 

 tissue as a whole. 



The following will serve to illustrate the method of 

 experimentation.^ Tissue which had in sea water a net 

 resistance of 770 ohms was placed in a solution of NaCl 

 0.52 M. In the course of 5 minutes the resistance fell to 

 580 ohms, or 75.32% of the original resistance.* When 



^O/. Hober (1914) Kap. 8, 9 und 13. 



'Of. Osterhout (1912, B) . 



'Cf. Osterhout (1915, B). 



* Complete recovery after such a large increase of conductance is not 

 always obtainable unless the material is in good condition and is freshly 

 collected. Even in such material a lot will occasionally be found in which 

 recovery is poor. 



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