PHTSIOLOGT 21 



enables us to place the study of injury upon a 

 quantitative basis. As the result of this we are 

 able to formulate a definite conception of the 

 mechanism of recovery. We find that if injury 

 in a solution of sodium chloride amounts to five 

 per cent, the tissue recovers its normal resistance 

 when replaced in sea water. But if the injury 

 amounts to twenty-five per cent, recovery is in- 

 complete j instead of returning to the normal 

 the resistance rises to only ninety per cent of the 

 normal. The greater the injury the less complete 

 the recovery. When injury amounts to ninety 

 per cent there is no recovery. 



This is of especial interest, since in physio- 

 logical literature it seems to be generally as- 

 sumed that when recovery occurs it is always 

 complete, or practically so, as if it obeyed an "all 

 or none" law. But it is evident that partial re- 

 covery may be easily overlooked unless accurate 

 measurements can be made. This fact may serve 

 to illustrate the importance of quantitative 

 methods in the study of these fundamental 

 problems. 



The significance of this method is further 



