Immunity of Lower Organisms to Ethyl Alcohol 587 



individual differences in their susceptibility to alcohol — -some 

 quickly adjusting themselves to it, others doing this v^ith greater 

 difficulty. 



Similar variability in results may be due to the fact that the 

 acclimatizing medium is too strong or too weak. In either case 

 there may be entire lackof immunity, or immunity may be deferred. 

 Lack of immunity may be due either to a medium too weak to 

 produce any effect, or one so strong as to produce lasting injury. 

 Deferred immunity may be due to the fact that the medium is so 

 weak that a long period is necessary for producing an acclimatiz- 

 ing effect, or it may come in a stronger solution when the first 

 effect is injurious, but is later replaced by the acquirement of 

 immunity. 



In several cases I have noticed that animals tested soon after 

 subjection to the acclimatizing medium showed a decrease in 

 resistance. This in some cases lasted several hours; in others it 

 was of short duration and was followed by evident adjustment. 



In an acclimatizing fluid of medium strength, an early evidence 

 of immunity may be expected from average animals by the end 

 of the fourth or fifth hours. 



The degree of possible tolerance reached evidently depends 

 upon factors similar to those which we have just set forth. 

 Among these may be especially mentioned — the effects of differ- 

 ent percentages of the acclimatizing media, the period of time 

 during which the animals are subjected to such media, and the 

 condition of the organisms at the time of subjection. 



In my work upon type F, a medium of i per cent alcohol has 

 been found most satisfactory. It has, therefore, been adopted 

 as the standard acclimatizing fluid in which all of the animals 

 of A, with but few exceptions, have been reared. If the medium 

 in which the animals are kept be of a strength lower than i per 

 cent the immunity produced by it may be expected to be propor- 

 tionately less in degree at a given time than that from a i per 

 cent medium — provided, of course, the strain suffers no perma- 

 nent injury from this latter strength. 



Using then a i per cent solution of alcohol as a unit we may pro- 



