Ivimumty of Lower Organisms to Ethyl Alcohol 593 



produced in E, the latter should show in such a case as that given 

 in Experiment III, p. 581 (the highest ever observed for E), a 

 resistance of 421.6 seconds (control 282 X 1.4951) instead of 

 375, as actually appeared. Thus the immunity indicated was at 

 best of a low degree. This low degree taken in connection with 

 the inconstancy of the results for that type makes the evidence for 

 its immunization scanty indeed. In type F, on the other hand, 

 the increase in resistance was marked and constant, so that the 

 immunization due to a residence in weak alcohol is evident. 



Evidence as to the existence of immunity to alcohol shows itself 

 in various other ways, besides an increase in the period of resist- 

 ance. The two types E and F showed also many differences in 

 these other respects. Thus in type E the normal resistance of 

 the control specimens was remarkably high and constant. The 

 average period of resistance to 6 per cent alcohol of 100 experi- 

 ments with unacclimatized specimens of type E was 267.9 sec- 

 onds. If this be compared with the resistance period for the con- 

 trols of E, as given in the foregoing experiments, the similarity 

 is very striking. On the other hand, the increase of resistance in 

 type E, due to keeping the animals in weak alcohol, was very incon- 

 stant. 



In these respects the animals of type F offer a contrast to those 

 of type E. In type F the natural resistance of the control animals 

 varied considerably at different times, but the increase in resist- 

 ance due to remaining in weak alcohol was uniform, so that there 

 was an almost constant ratio between the resistance periods of the 

 unacclimatized and the acclimatized specimens. 



Furthermore, the response of the acclimatized animals of type 

 F to the killing fluid was different from that of unacclimatized 

 forms. It might be supposed that an increase in resistance would 

 manifest itself especially in making the animals better able to 

 preserve themselves intact from the action of the drug. Such was 

 not my observation. On the contrary the acclimatized animals 

 of type F usually suffered an early distortion. In these animals 

 life, to outward appearances, was well nigh extinct at the end of a 

 few seconds— the cilia beating unsteadily. Near the end of the 

 first minute, however, they revived and death was delayed often 

 for a considerable period of time. 



