498 



A.H. Estabrook 



Preliminary Experiments on the Effect of NaCi on the Form and 

 Dimensions of Adults 



Adult Paramecia put into a NaCl solution died after some 

 time. They first became thin, then shorter and much thinner, 

 and slowly died. The appearance of Paramecia as they are dying 

 is very characteristic; they become much swollen, sometimes 

 twice as thick as normal, sometimes longer, or thev may be 

 shorter; the protoplasm contains many vacuoles; the animals 

 swim about slowly. The exact moment of death is difficult to 

 determine in this condition, as vitality seems to remain a long 

 while, and even after they have become motionless, they may 

 sometimes be made to move again by stimulating them with a 

 capillary rod. 



To determine the effect on dimensions, a large number of speci- 

 mens were put into a ^^ NaCl solution (see table VI). 



TABLE VI 



Dimensions of adull Paramecia in ^.^ NaCl. 



At intervals of ^ minutes, about 50 were taken out, killed and 

 measured. Most of the animals died about 10 to 20 minutes 

 after being put into the salt, but some, more resistant than the 

 others, remained alive 60 minutes. The curve (Fig. i), plotted 

 from these figures, is thus based on different numbers of individuals 



