392 



BOTANICAL GAZETTE 



[may 



respiratory rate (curve D) is greatly increased and reaches its 

 maximum during the second period. This is followed by a rapid 

 decrease in the rate during the third and fourth periods, although 

 the rate is still above the normal. After the fourth period a more 



REL, RATE OF RESP. 

 REL.AMT.OFRESP. 



60 



120 MINUTES 



Fig. 3. — Curves (unbroken lines) showing effect of sea water containing A, 0.1 

 per cent acetone; B, 0.51 per cent acetone upon relative rate and relative amount of 

 respiration of Laminaria (identical for these substances); C, effect of sea water con- 

 taining 17.4 per cent acetone (unbroken line) upon relative amount of respiration; 

 Z), effect of sea water containing 17.4 per cent acetone (unbroken line) upon relative 

 rate of respiration; controls in sea water (broken lines); see tables III A to IIIC; 

 each control bears the same letter (with a prime) as the experimental curve. 



gradual decline begins, so that even at the end of the experiment 



covering 2 hours and 48 min. the respiratory rate is still sHghtly 



above the normal. 



TABLE III A AND B 



Two PERIODS (23 MIN. EACH) IN SEA WATER FOLLOWED BY 2 EQUAL PERIODS IN SEA 

 WATER CONTAINING O . I PER CENT ACETONE, FOLLOWED BY 2 SIMILAR PERIODS 

 IN SEA WATER CONTAINING O.51 PER CENT ACETONE 



Solution 



Sea water 



Sea water containing o . i per cent 



acetone 



Sea water containing o . i per cent 



acetone 



Sea water containing 0.51 per cent 



acetone 



Sea water containing 0.51 per cent 



acetone 



Change in PH 



Relative rate of respiration 



37-7.64 = 0.73 

 37-7.64 = 0.73 



37-7-65 = 0.72 



37-7-65 = 0.72 



37-7-65=0.72 



37-7-63 = 0.74 



o.72-e-o.73=o.99 

 0.72-^0.73 = 0.99 

 0.72-^0.73 = 0.99 

 0.74-^0.73 = 1.01 



