CHAPTER III 



BACILLUS coli communis was selected in the earlier 

 experiments for the following reasons: (1) It is easily 

 obtained at any time from the normal feces of man. (2) It 

 is quite stable in artificial cultures, varying but little, if 

 transplanted from day to day, in its effects upon experi- 

 mental animals. (3) It elaborates no extracellular poison, at 

 least under ordinary conditions and in beef-tea cultures. 



Our early findings were reported in 1901, * and these, 

 confirmed and enlarged by subsequent work, will be briefly 

 reported as follows: 



1. The poison is contained within the bacterial cell 

 from which it does not, at least under ordinary conditions, 

 diffuse into the culture medium. 



This was demonstrated by the following experiment, 

 which was repeatedly made, and always with the same result : 

 Beef-tea cultures of the colon bacillus, grown for three 

 weeks or longer, in the incubator, were filtered through 

 porcelain. From 8 to 10 c.c. of the clear, sterile filtrate 

 was injected intra-abdominally in guinea-pigs. The animals 

 thus treated were restless and evidently in pain for some 

 minutes after the injection, probably due to the volume of 

 the fluid and its slightly irritating character, but gave no 

 other evidence of any effect of the injection. 



As controls to the above, other guinea-pigs received 

 intra-abdominally 0.25 c.c. of the same culture unfiltered, 

 and all died within twelve hours. It will be understood 



1 Trans. Assoc. Amer. Phys., xvi, 201. 



