352 



BOTANICAL GAZETTE 



APRIL 



amount of respiration are approximately double that of the normal, 

 although the tissue is shown by the method of electrical resistance 

 to be dead. This is brought out very strikingly in fig. i where 

 we plot as ordinates the relative amount of respiration (curve C, 

 table I A), relative rate of respiration (curve B, table I A), net 

 resistance as percentage of that at the start (curve A, table I B) 

 respectively (unbroken lines). When the relative rate of respira- 

 tion has practically reached zero (curve B) the relative amount of 



°/4rest. 



REL.RATEOFRESP. 

 REL. AMT. OF RESP. 



MINUTES 



Fig. I. — Curves showing effect produced by sea water, approximately saturated 

 with ethyl bromide, upon relative amount and relative rate of respiration, and upon 

 net electrical resistance of Laminaria: curve A, ordinates represent net resistance as 

 percentage of that at start; curve B, ordinates represent relative rate of respiration; 

 curve C, ordinates represent relative amount 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. 



respiration is above unity. At the end of 60 minutes, when the 

 tissue can be considered dead, the relative rate is seen to be about 

 double that of the normal rate. 



Table II A shows the effect produced by sea water containing 

 17.4 per cent (by volume) acetone, made up to the electrical 

 conductivity of sea water by the addition of concentrated sea 

 water, upon the relative amount and relative rate of respiration 

 of Laminaria. At the end of 2 . 5 hours the rate of respiration is 

 still above the normal rate, while the relative amount of respira- 



