33 O LOUISE A. ANDERSON. 



Two types of experiments were carried out: short exposures of 

 a few hours to alkaline solutions, and long exposures of a week 

 or more. Three experiments, that is, three flasks of worms, were 

 generally carried on simultaneously. 



2. Short Time Experiments. In these experiments the rate 

 of oxygen consumption of the worms was tested for two successive 

 hours in normal well-water, pH 7.6 to 7.8. The water was then 

 made alkaline by adding NaOH in varying amounts, giving a pH 

 of 8.0 to 9.2 by intervals of 0.2 pH, or by adding NH 4 OH similarly 

 to alkalinities varying from pH 8.0 to 8.8. The rate of oxyger. 

 consumption was then tested in this alkaline water during the first 

 third, and generally also fifth hours of exposure to it, freshly 

 made alkaline water being used for each determination. As stated 

 above, carbonate-free water was employed for alkalinities greater 

 than pH 8.6. Twenty-three experiments were performed with 

 sodium hydroxide and twelve with ammonium hydroxide. Table 

 I. gives a typical experiment with each pH used for each of the 

 two alkalies. The average per cent, of increase is based on all 

 of the figures obtained in the alkaline solution. Table II. pre- 

 sents a summary of all of the short time experiments showing also 

 the minimum, maximum, and average change in respiratory rate 

 These tables show that the respiratory rate was sometimes de- 

 creased in alkaline solution but was more generally accelerated 

 The normal variation in respiratory rate, based on twenty experi- 

 ments where the respiration was determined in normal water for 

 two successive hours, was 7 per cent. Only figures showing more 

 than 7 per cent, alteration of the respiratory rate are therefore 

 significant. From Table II. it can be seen that the higher al- 

 kalinities give generally a significant acceleration of the rate of 

 oxygen consumption. 



The worms would not survive alkalinities greater than those 

 given in the table. They would live indefinitely in water made 

 alkaline by NaOH to pH 9.0, but only twenty-four hours at pH 

 9.2. They were immediately killed in NH 4 OH at pH 9.0. These 

 results indicate that the action of alkali cannot be attributed solely 

 to the hydroxyl ion. 



It should be stated that the oxygen consumption of Planaric 

 is independent of the oxygen content of the waler at all ordinary 



