356 



BOTANICAL GAZETTE 



[april 



made up to the conductivity of sea water by the addition of con- 

 centrated sea water. The free acid of the formaldehyde was first 

 neutraHzed by the addition of a Httle sodium carbonate. This is 

 allowable for the purposes of the present investigation, for its 

 effect would be to make the amount of CO2 produced appear some- 

 what less than was actually the case. At the end of 4 hours the 

 relative rate of respiration was still above the normal, while the 



7oREST. 



REL.RATEOFRESP. 

 RELJIMT.OJFRESP. 



MINUTES 



Fig. 3. — Curves showing effect produced by sea water containing 24.2 per cent 

 (by volume) of ethyl alcohol upon relative amount and relative rate of respiration and 

 upon net electrical resistance of Laminaria: curve A, ordinates represent relative 

 amount of respiration; curve B, ordinates represent net resistance as percentage of 

 that at start; curve C, ordinates represent relative rate of respiration (unbroken lines) ; 

 controls in sea water (broken lines) ; each control curve bears same symbol and letter 

 (with a prime) as experimental curve; abscissae represent time in minutes. 



relative amount of respiration was much above the normal. At 

 this concentration of formaldehyde Laminaria is practically dead 

 in 180 minutes. In table IV, however, after 280 minutes the rela- 

 tive rate of respiration of Laminaria is still above normal, while 

 at 180 minutes the relative rate is far above normal. 



For purposes of comparison other methods of kilhng were tried. 

 By making preliminary conductivity experiments with Laminaria, 

 it was found that when it is dried upon cheesecloth in the sunlight 

 in a current of dry air, we can consider the tissue practically dead 



