THE PERMEABILITY OF CELLS 547 



freely. Ammonia, likewise, must affect the membrane in time 

 since it produces change in behavior, vesicle formation, cessa- 

 tion of movement and finally death, but the changes produced 

 bear no relation to the time of entrance. 



Even in very dilute solutions NH4OH and the amines are able 

 to 'decolorize' stained Paramoecia but it takes a longer time. 

 Yet in equivalent molecular concentrations of KOH, NaOH, 

 etc., the animals sometimes retain their red color for 24 hours. 

 Generally they are found to be colorless in chat time. The de- 

 colorization is not due to the slow entrance of alkali because the 

 same red individuals placed in distilled water are found to be 

 colorless after 24 hours, although otherwise unchanged. A com- 

 parison after a shorter time, six hours, must be made. The results 

 are given in table 6. 



NH4OH enters the cell readily and sets free a small amount of 

 the neutral red base from its granule combination. The freed base 

 diffuses out into the medium and more NH4OH enters. Thus the 

 process is repeated uatil the organism is quite colorless. That 

 the same decolorization does not take place in KOH must be due 

 to the fact that the KOH does not enter freely. 



In very weak concentrations (to^to) NH4OH fails to affect the 

 red color of stained Paramoecia at all. This concentration is 

 presumably below the limit necessary to free the neutral red 

 from its combination with the granules. 



b. Marine eggs: In the following experiments the eggs of both 

 Toxopneustes and Hipponoe were used. The sea water at Boca 

 Grande, 11 where the experiments were performed is markedly 

 alkaline to neutral red and faintly so to phenolpthalein. If 

 Toxopneustes eggs, unfertilized, are placed in 100 cc. sea water 

 -|- 1.2 cc. 1*^, NaOH sufficient alkali does not enter them to turn 

 the neutral red yellow for over three hours. If chloroform is 

 added to the sea water, the eggs almost instantly turn yellow. 

 Chloroform likewise causes the eggs to swell (cytolysis), an effect 

 prevented in plant cells by the presence of a cellulose wall, and 

 the penetration of the alkali might be connected with the swell- 



" About twelve miles west of Key West and sixty miles east of Tortugas. 



