338 LOUISE A. ANDERSON. 



condition in alkaline water (pH 9.0). A cover was sealed on 

 airtight. As the oxygen was absorbed by the alkaline pyrogallate, 

 the worms began to die. The results of one such experiment are 

 graphed in Fig. 5, the solid line representing the control worms, 



60 

 So 



40 

 30 

 20 

 10 



24 25 20 27 28 2y jo j/ 32 jj jj jj ] 22 



FIG. 5. Graph of disintegration gradient of worms exposed to NaOH solution 

 and tested in alkaline solution in lack of oxygen experiment. Heavy line represents 

 worms in ordinary water and broken line worms exposed to alkali. Record was 

 not taken until disintegration began, i.e., the twenty fourth hour. Hours are on 

 the abscissa and stages of disintegration on the ordinate. 



the dashed line, the experimental worms. In several experiments 

 of this kind it was always found that the worms died faster from 

 lack of oxygen at pH 9.0 than at pH 8.0. 



3. Experiments with Ultraviolet Radiation. Comparable lots 

 of worms were exposed to ultraviolet radiation from a Cooper- 

 Hewitt machine for a duration known to be lethal, one lot at pH 

 8.0, the other at pH 9.0. The worms were continually agitated 

 during the exposure to insure uniform radiation. In all trials, 

 the worms in the more alkaline water died more rapidly than those 

 at the lower alkalinity. Death of course occurs only some hours 

 after exposure to the radiation. 



These experiments indicate that planarians are more susceptible 

 to toxic chemicals and to lethal conditions when exposed to them 

 in water of increased alkalinity, which is not in itself injurious. 



4. Susceptibility to Alkali.- The question was raised whether 

 the worms are able to acclimate to increased alkalinity. The long 

 time experiments did not suggest that this was the case within 

 two weeks' exposure, since the acceleration of the respiratory rate 



