16 THE MECHANISM OF INJURY AND RECOVERY 



If, however, the exposure to the solution of NaCl lasts longer the 

 tissue does not recover its normal resistance when returned to sea 

 water. After prolonged exposure recovery is much less complete and 

 as the tissue approaches the death point there seems to be no recovery 

 when it is removed from the solution of NaCl and kept in sea water 

 under normal conditions. 



Fig. 1 shows that the recovery curves rise to certain definite levels 

 and then run horizontally. If the conditions are favorable they may 

 maintain this horizontal course for days; but if the control falls they 

 also fall. 



300 600 QOOmin. 



Fig. 1. Curves showing electrical resistance of Laniinaria agardhii in NaCl, 

 0.52 M (unbroken line), and recovery in sea water (dotted lines). The figure at- 

 tached to each recovery curve denotes the time of exposure (in minutes) to the 

 solution of NaCl. 



Another aspect of recovery is illustrated by the results obtained in 

 mixtures of NaCl and CaClo. Curve C in Fig. 2 shows the behavior 

 of tissue placed in a solution containing 97.56 rnols of NaCl to 2.44 of 

 CaCl^; its electrical resistance falling in 37.5 hours to 72.87 per cent 

 of the original value in sea water. In a solution containing 85 mols 

 of NaCl to 15 mols of CaCl2 (Curve A) the resistance fell in the same 

 time to practically the same point (72.47 per cent). 



When these two lots of tissue were replaced in sea water they be- 

 haved differently. The resistance of the first lot rose to 78.2 per cent 



