360 



BOTANICAL GAZETTE 



[april 



By determining the electrical resistance it was found that 

 Laminar ia is killed by exposure to 35° C. for 70 minutes. The 

 respiration before and after such exposure was then determined. 

 During the treatment at 35° C. the material was removed from the 

 tubes and placed in a large volume of the sea water kept at 35° C. 

 The results are given in table VII A. After the exposure to 35° C, 

 the relative amount and rate of respiration had fallen considerably 

 below the normal. This might be expected on the ground that 

 oxidizing enzymes are injured or destroyed by heat. 



TABLE V A 

 Change in PH value of sea water produced by respiration of Laminaria during 6 



PERIODS (30.5 MIN. each) IN SEA WATER; AT END OF SECOND PERIOD MATERIAL DRIED 

 IN CURRENT OF AIR IN SUN FOR 1 39 MINUTES; MATERIAL THEN PLACED IN SEA WATER 

 AT 22° C. FOR 15 MINUTES BEFORE BEGINNING THIRD PERIOD. 



It is well known that. severe injury causes a considerable rise 

 in the respiration, and it seemed desirable to make such experi- 

 ments with Laminaria. After the normal respiration of a piece 

 of tissue had been determined, the material was removed from the 

 tube and finely macerated (by means of the jagged end of a tube 

 of Pyrex glass) on a piece of tested filter paper. The minced 

 Laminaria was put back into the tube and rinsed 6-10 times with 

 sea water until none of the liberated pigment could be distinguished 

 in the sea water. Fresh sea water was then added and the respira- 

 tion determined. The results are given in table VIII, the control 

 data being given in table V. In table VIII it will be observed 

 that the relative amount and relative rate of respiration are both 



