546 EDMUND NEWTON HARVEY 



ectoplasm bearing cilia, but swim about normally although slowly for 

 over fifteen minutes. A much more rapid rate of swimming is regained 

 soon after the slowing, which takes place when first subjected to the 

 action of the solution. 



■6^0^ NaOH — Paramoecia placed in this solution swim rapidly forward 

 but in less than one quarter minute they stop short and give the avoid- 

 ing reaction. Many stop suddenly and swim rapidly backward. Change 

 in shape begins immediately and in three minutes they are much shorter 

 and broader and move slowly forward, circling about their long axis. 

 In four minutes clear drops (vesicles) and also clear protrusions appear 

 on the surface. The protrusions may contain many red stained granules. 

 After eight minutes some individuals have burst and the neutral red, 

 which up to this time has been red, immediately turns yellow. Most 

 of the Paramoecia burst before twelve minutes but a few are still mov- 

 ing very slowly and appear as red as when first placed in the solution. 



Essentially, the series of changes undergone in the two solu- 

 tions is the same. The NH4OH meets no resistance at the sur- 

 face and the red color may be seen to change gradually to yellow, 

 which diffuses out leaving the organisms colorless, from the 

 moment the}^ are placed in the solution. The change is complete 

 before droplets appear at the surface or movement ceases. NaOH 

 does not enter until after movement has ceased and the organism 

 is enormously swollen and has lost all semblance to its original 

 shape. Red granules may be present directly under the surface 

 yet they remain red. Once the NaOH does begin to enter it does 

 so rapidly and what is left of the Paramoecia becomes first yellow 

 then colorless, in less than two minutes from the time the alkali 

 begins to pass in. 



We must draw the conclusion, that the NaOH produces the 

 changes in behavior, the vesicle formation, the cessation of move- 

 ment and the final death of the animal, all by an effect on its sur- 

 face membrane. So long as NaOH alone was studied I could 

 never be sure that a small amount of NaOH, too small to affect 

 the red stained granules, did not enter and was not responsible 

 for the observed changes. But the comparison with NH4OH 

 shows how low the OH ion concentration that is required to de- 

 compose the red granules really is provided the alkali may enter 



