586 J. Frank Daniel 



given In Experiment III. This gives a ratio of 1.3297 + to i for 

 the resistance period of the acdimatized animals as compared 

 with that for the controls. This, however, as we shall see later, 

 is much less marked than the results of even the least striking ex- 

 periments for type F. But in degree it might well be classed as a 

 case of immunity were it but constant. Ranging, however, from 

 this maximum down were other experiments of the same kind 

 which showed less or even no increase in resistance whatsoever. 

 The latter extreme is shown in Experiment VI. 



This variability of results was so noticeable that at no time has 

 the evidence for the immunity of this type been convincing. 



2 Study of Type F 



From the preliminary study we saw that the animals of type 

 F responded to acclimatization in a weak medium of alcohol by 

 an increase in the resistance to a known fatal dose from a period 

 of 162 seconds to 301 seconds. Further, when this type was kept 

 for a longer period in a weak medium which was gradually in- 

 creased in strength, it finally came to live in a concentration suf- 

 ficient to have proved destructive before acclimatization. 



We may now proceed to a study of type F, in which something 

 of the nature of the immunization — ^when it begins, when it reaches 

 its maximum degree of increase, and the like — may be sought. 



The method employed in the preliminary experiment as modi- 

 fied in the study of type E, was followed in detail. Of the two 

 tests for immunity given, that depending upon the increased period 

 of resistance to a fatal dose was adopted as being the more advan- 

 tageous, especially in point of time. 



Incipient immunity may vary considerably as to the time ot its 

 appearance. In this range of variability several factors are in- 

 volved. 



One strain of animals at a given time may show immunity 

 slightly advanced before another strain of the same type has ceased 

 being stimulated to activity from subjection to the medium. What 

 is true of different strains is equally true of individuals of the same 

 strain. In other words single cells, like higher forms, show marked 



