BACILLUS COLI COMMUNIS 393 



chicks and their entire environment sterile for seventeen days. During 

 this time they lost weight, did not thrive, and some of them were mori- 

 bund at the end of the second week, in marked contrast to the healthy, 

 well-nourished controls, fed in the same way, but under ordinary 

 environmental conditions. Although insufiicient work has been done 

 upon this important question, and no definite statement can be made, 

 it is more than likely that the function of the Bacillus coli in the intes- 

 tine is not inconsiderable if only because of its possible antagonism to 

 certain putrefactive bacteria, a fact which has been demonstrated in 

 interesting studies by Bienstock ' and others.^ 



Pathogenicity. — The pathogenicity of the colon bacillus for animals 

 is slight and varies greatly with different strains. Intraperitoneal in- 

 jections of 1 c.c. or more of a broth culture will often cause death in 

 guinea-pigs. Large doses intravenously administered to rabbits may 

 frequently cause a rapid sinking of the temperature and death with 

 symptoms of violent intoxication within twenty-four to forty-eight hours. 

 Subcutaneous inoculation of moderate doses usually results in nothing 

 more than a locaUzed abscess from which the animals recover. It is likely 

 that, even in fatal cases, death results chiefly from the action of poisons 

 liberated from the disintegrating bacteria and not from the multipli- 

 cation of the bacilli themselves, for often no living organism can be 

 found unless large doses are given. 



In man, a large variety of lesions produced by Bacillus coli have 

 been described. It is a surprising fact that disease should be caused 

 at all, in man, by a microorganism which is so constantly present in 

 large numbers in the intestine and against which, therefore, it is to be 

 expected that a certain amount of immunity should be developed. A 

 number of explanations for this state of affairs have been advanced, 

 none of them entirely satisfactory. It is probable that none of the poi- 

 sonous products of the colon bacillus is absorbed unchanged by the 

 healthy unbroken mucosa and that, therefore, the microorganisms are, 

 strictly speaking, at all times, outside of the body proper. Under these 

 circumstances, no process of immunization would be anticipated. It 

 is also possible that, whenever an infection with Bacillus coli does occur, 

 the infecting organism is one which has been recently acquired from 

 another host, having no specific adaptation to the infected body. Viru- 

 lence may possibly be enhanced by inflammatory processes caused by 

 other organisms. Considering the subject from another point of view, 



' Bienstock, Arch. f. Hyg., xxxix, 190L 



2 Tissier and MarteUy, Ann. de I'inst. Pasteur, 1902. 



