664 STUDIES ON RESPIRATION. XVn 



perhaps be explained as a purely mechanical disturbance due to the 

 great differences in osmotic pressure as the result of which the 

 tissue must remain about 30 minutes in normal sea water before the 

 readjustment is complete. 



Fig. 2 shows that the effects of strongly hypotonic sea water are 

 similar to those of strongly hypertonic, except that the lowering of 

 respiration is not so pronounced. Here also we observe all degrees 

 of recovery depending on the length of exposure to the solution. 



,-A- 



50k>/o.— 





Fig. 1. Curves showing rate of respiration of Laminaria (expressed as per cent 

 of the normal). The normal rate represents a change from pH 7.78 to 7.36 in 

 from 1| minutes to 2 minutes, depending upon the amount of material used. 

 The solid lines show rate of respiration while tissue was exposed to hypertonic 

 sea water (sp. gr. 1.130, A = — 9.37 approximately). The dotted lines show 

 stages of recovery after the tissue was put back in normal sea water. Each curve 

 represents a typical experiment. The figure attached to each recovery curve 

 denotes the time (in minutes) of exposure to the solution of hypertonic sea water; 

 thus the uppermost curve represents recovery, after an exposure of 5 minutes. 



The question naturally arises as to what happens when these pieces 

 of tissue are kept longer than 20 hours in running sea water. This 

 was carefully investigated and it was found that every piece of tissue 

 which had been exposed to hypertonic or hypotonic sea water died 

 and disintegrated much sooner in running sea water than the normal 

 piece of tissue kept in the same vessel and treated in the same manner 

 except that it was not exposed to hypertonic or hypotonic solutions. 



