Effect of Chemicals on Growth 



493 



to the distilled water, the specimen was washed once in a con- 

 siderable quantity of the same distilled water, in order to remove 

 any trace of hay infusion remaining on it. At the end of five 

 minutes specimens in the hav infusion had increased in length 

 from 139.5 ^° ^53-3 rnicrons. Those in the distilled water had 

 grown precisely the same amount. Now, however, the injurious 

 action of the distilled water began to show by the fact that the 

 specimens in it began to shorten and thicken, while those in the 

 hay infusion continued to increase in length and decrease in thick- 

 ness. At the end of fifteen minutes the control specimens measured 

 159.6 X 42.7 microns, those in the distilled water 149.7x53.1 

 microns. The latter are thus actually shorter than they were ten 

 minutes earlier. At the end of thirty minutes they were all dead, 

 while those in the control were strong and active. The compara- 

 tive measurements are given in Table I. 



TABLE I 



Comparative measurement in microns of Paramecium in pure distilled water and in hay infusion 



It is notable that a certain amount of growth did occur in the 

 distilled water in the first five minutes, in spite of the fact that 

 the latter is quickly injurious and soon fatal. It seems clear that 

 the injurious result was here due, as in Daniel's experiments, to 

 the sudden change from the fluid with the high salt content to one 

 with a low salt content. 



