THE BACTERIOPHAGE AND THE BACTERIUM 87 



teriophage, and further, that when, by subculture on agar, they 

 lose their resistance they also become agglutinable. Inagglu- 

 tinability appears to be a property of the bacteria which resist 

 the bacteriophage. 



The vitality of resistant bacteria is much greater than that of 

 normal bacilli. For example, with the Shiga dysentery organism 

 whose vitality is weak (there are but few strains cultivable after 

 one month, none among the numerous strains with which I have 

 worked have remained alive without subculturing for more than 

 two months), all of the colonies on agar of the resistant Shiga 

 substrain are still cultivable after eighteen months. 



The virulence of bacteria which are resistant to the bacterio- 

 phage is likewise considerably greater than that of normal bacilli. 



Whatever may be the nature of the resistant bacteria, and 

 whatever may be their form, there is no doubt but that they can 

 return to the normal form with normal properties. They then 

 behave as the bacteria of the same species which were used to 

 prepare the initial suspension upon which the bacteriophage 

 acted. In a word, there can be no question either of an accidental 

 contamination or that they are visible forms of the bacteriophage. 



With a coccoid culture of B. dysenteriae Shiga the following 

 biologic reactions have been effected, reactions which indicate 

 that these cocci conserve the general properties of the normal 

 dysentery bacillus: 



a. The injection into a rabbit of such cultures causes the death 

 of the animal with paralysis and intestinal lesions identical with 

 those observed in animals killed by the inoculation of typical 

 dysentery organisms. 



b. Rabbits immunized with carefully graded doses of such 

 cultures are protected against a surely fatal dose of typical dysen- 

 tery organisms. 



c. The serum of rabbits which have been treated with injections 

 of coccoid cultures contain an amboceptor which will fix com- 

 plement in the presence of normal bacilli. 



Zoogleic form 



Microscopic examination of the agglutinate formed in liquid 

 media by bacteria which are endowed with a high resistance, 

 and also of colonies which are mucoid on agar, show that the 



