332 



LOUISE A. ANDERSON. 



alkaline water as per cent, decrease or increase from this. The 

 alkalinity in terms of pH is given on the abscissa. The solid line 

 represents the results with NaOH, the dashed line with XH 4 OH. 

 As already explained only differences greater or less than 7 per 

 cent can be taken as significant. In the case of XaOH the ex- 

 periments at pH 8.4 to 9.2 show on the average an increase above 

 the normal variation, but there is apparently no relation between 

 amount of acceleration and degree of alkalinity. The drop at 

 pH 8.8 and 9.0 is probably not significant. In the case of am- 

 monia the curve rises steadily with increasing alkalinity but prob- 

 ably only the increase at 8.8 is significant. 



T40 



'jo 



120 



1 10 



too 



9 



&0 



8.2 



&6 



FIG. i. Graph compiled from the average peicentages of increase and decrease 

 in respiration rate of all the short time experiments. See Table II. Per cent, 

 of increase or decrease, normal respiration being taken as 100, on the ordinate 

 and pH on the abscissa. Heavy line shows experiments in NaOH and broken 

 line the experiments in NH4OH. 



3. Long Time Experiments. These experiments consisted in 

 determinations of the rate of oxygen consumption at frequent 

 intervals in worms exposed continuously to alkaline water for 

 periods of one to two weeks. Considerable difficulty was encoun- 

 tered in these experiments because the water would not remain at 

 a definite alkalinity on account of the carbon dioxide given off by 

 the animals. Various methods of keeping the water alkaline were 

 suggested and were tried out. The carbonate- free water could not 

 be used in the long time experiments, as. being unbuffered, it 

 quickly became acid from the carbon dioxide given off by the 



