576 J. Frank Daniel 



marked activity. After having remained in the medium for a day 

 an acceleration in division w^as observed which resuked in cells 

 of smaller size. Type F, on the contrary, in this weak solution 

 of alcohol showed slight increased activity upon subjection, and 

 practically no increase in the rate of division upon remaining in 

 the medium for a short period of time. 



When these two types had been kept in a weak solution for some 

 time, and were then placed in stronger alcohol, they showed still 

 more important differences. Type F gained a marked immunity 

 as a result of remaining in the weak solution, while type E showed 

 very little effect of this sort. This difference will be brought out 

 in full in the following investigations. 



2 Method of Studying Immunity 



Tests for the immunity resulting from a weak solution of alcohol 

 may be made in one of two general ways. Either (i) the com- 

 parative resistance period of alcoholized and control (normal) 

 animals to a known fatal percentage may be determined, or (2) 

 the ability of alcoholized animals to live in a solution which was 

 previously destructive may be tested. 



The two may be stated more comprehensively in the following 

 questions: 



1 What is the effect produced upon the general resistance of 

 an organism by rearing it in a weak chemical, for example alcohol, 

 and testing it to a strong solution of the same substance. 



2 Can animals by living in a weak concentration of a substance 

 be made to survive a stronger percentage of the same .^ For 

 example, can an organism which is normally killed within a few 

 hours by a 2 per cent solution of alcohol be made to live in the 

 same strength ? 



3 Experimental 



As has been mentioned, the answer to these questions depends 

 upon the animals used. Type E, kept for different periods of 

 time in a weak medium and then tested to a stronger percentage, 

 did not give marked evidence for immunity on either of the tests 

 mentioned above. Type F, on the other hand, reared similarly. 



