F. G. GUSTAFSON 



187 



rapid decrease, so that in from 6 to 10 minutes the rate was back at 

 normal. At the end of an hour respiration was nearly at a standstill 

 (Fig. 2, Curve C). 







60MIN. 



Fig. 2. Curves showing the effect of ether on the respiration of Aspergillus 

 niger. Curve A, in 3.65 per cent ether; Curve B, a different culture in 3.65 per cent 

 ether; Curve C, in 7.3 per cent ether. The horizontal part of the curves shows 

 respiration in tap water before exposuie to ether. Dotted line shows respiration 

 of a control in tap water. The normal rate (which is taken as 100 per cent) cor- 

 responds to a change from pH 7.60 to pH 7.25 in 3.25 minutes for Curve A and 

 in 3 minutes for Curves B and C. Curve A represents the average of four ex- 

 periments; Curves B and C, the average of five experiments. Probable error, 

 less than 2.4 per cent of the mean. 



The results with ether are shown in a different manner in Fig. 3. 

 A number of experiments on recovery were conducted with 7.3 

 per cent ether. The result of these experiments was, that if respiration 



