0. L. INMAN 665 



Pieces of tissue that showed complete recovery were found to live 

 longest, as expected, but none of these remained normal more than 

 seven days while the untreated showed a normal rate of respiration 

 after eighteen days. Those pieces that showed partial recovery were 

 marked by a fall in the rate, usually at the end of three days, but in 

 a few cases not until the end of five days. Where there was no recov- 

 ery the pieces turned green and soon disintegrated. 



A series of experiments was made in which pieces of Laminaria 

 were placed in isotonic sodium chloride (0.52 m for Woods Hole sea 

 water) and the respiration measured at the end of an hour. The 



20_ , 



20 ^ 





io ib 



HOURS 



Fig. 2. Curves showing rate of respiration of Lamifiaria (expressed as per 

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

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

 solid lines show rate of respiration while tissue was exposed to hypotonic sea 

 water (sp. gr. 1.0023, a = —0.187). The dotted lines show stages of recovery 

 after the tissue was put back in normal sea water. Each curve represents a typi- 

 cal experiment. The figure attached to each recovery curve denotes the time 

 (in minutes) of exposure to the solution of hypotonic sea water. 



pieces were then returned to running sea water and at intervals shown 

 by the points on dotted lines of Fig. 3, they were removed and the 

 rate of respiration determined. 



In this case some pieces of tissue were more affected than others 

 by the same length of exposure (due to the thickness of the fronds, 

 the temperature of the experiment, etc.) , and it is noticeable that the 

 greater the lowering of the respiration the less complete the recovery. 

 Here also it was found that the treated pieces of tissue lived but a 

 short time in running sea water as compared with the normal pieces. 



