6 10 y. Frank Daniel 



While in glycerin and methyl alcohol there was often little 

 evidence of decrease in resistance due to the previous acclimatiza- 

 tion in ethyl alcohol, there was clearly no marked advantage or 

 increase of resistance due to this cause. In both acid and alkali, 

 on the other hand, the resistance of the animals was lowered in a 

 marked degree by previous acclimatization to ethyl alcohol, 

 although this had greatly increased the resistance to alcohol itself. 

 This demonstrates in the clearest way the specificity of the immu- 

 nity due to a residence in alcohol. 



V SUMMARY AND CONCLUSIONS 



The foregoing investigations consist of a study of the acclimati- 

 zation of infusoria to ethyl alcohol, and the effects of this acclim- 

 atization on their resistance to other chemicals. 



1 In certain strains of Stentor coeruleus, and in Spirostomum 

 ambiguum, it was found that living for a few days in I per cent 

 ethyl alcohol increases the resistance of the animals to a stronger 

 solution of the same substance — ethyl alcohol. This increased 

 resistance is shown (i) in the fact that the organisms are not so 

 quickly killed in a lethal solution, (2) in the fact that they may 

 continue to live in a solution stronger than that in which they could 

 live before acclimatization. 



2 Different species of infusoria and different strains of the 

 same species, living under dissimilar environmental conditions 

 showed various degrees of normal resistance to alcohol, and very 

 different capacities for becoming acclimatized to it. 



In Stentor coeruleus one strain designated as E manifested a 

 high normal resistance, but this resistance was increased little or 

 not at all by remaining in i per cent alcohol; while another 

 strain F had a low normal resistance which was readily increased 

 by living in a weak acclimatizing medium. 



Incidentally, similar differences in the resistance of different 

 sorts of infusoria to other chemicals were observed. Thus, Spi- 

 rostomum withstood about eight times as concentrated a solution 

 of hydrochloric acid as did Stentor. Marked differences are like- 

 wise observable among individuals of the same culture when tested 

 for resistance to different chemicals. 



