188 



STUDIES ON RESPIRATION, II 



had risen and fallen again to normal and the material was then 

 taken out of the ether solution and put in a nutrient solution, it was 

 found on observing it 2 to 3 hours later that respiration was practi- 

 cally normal (Fig. 4, Curve B). If on the other hand the mater al 

 was allowed to remain in the ether solution until the rate had fallen 

 to about 60 per cent of the normal and then placed in nutrient solu- 

 tion recovery to normal was not obtained. From this it would seem 



107<,ETHER 



Fig. 3. Curve A shows the rate of respiration of Aspergillus niger in various 

 concentrations of ether after an exposure of 2 minutes. Curve B shows rate of 

 respiration after an exposure of 10 minutes. Curve C shows rate of respiration 

 after an exposure of 30 minutes. The dotted line shows the normal respiration. 



The figures expressing the per cent of ether should be corrected by multi- 

 plying by 0.73. 



that only the increase in respiration is reversible and that when a de- 

 crease takes place an irreversible reaction involving injury is going on. 



A 20 per cent solution (by volume) of acetone was also employed. 

 A very large increase took place, with the maximum during the second 

 period (Fig. 5, Curve B). This concentration of acetone was very 

 much less toxic than 7.3 per cent ether. 



Alkaloids usually have a special effect. For this reason it was 

 thought best to try caffeine as a representative of this group. Low 



