424 J. RUSSELL ESTY 



V. On February 6, 2 cc. of milk culture 8 was injected into a 551- 

 gram pig subcutaneously. Although this strain did not prove fatal in 

 two cases, local swelling occurred accompanied with gas and the for- 

 mation of an abscess. The reaction was not so violent as in some 

 cases although the animal lost 43 grams. Recovery took place in 

 three weeks. 



A second injection was given on March 23, 1917, the pig weighing 

 617 grams. Two cubic centimeters of a twenty-four hour old culture 

 19, which had previously proved pathogenic for guinea-pigs, was inocu- 

 lated subcutaneously and failed to produce a fatal necrosis. Emphy- 

 sematous crackling due to the formation of gas bubbles occurred, but 

 the reaction was not as severe as in other cases. In two weeks the pig 

 recovered from the second injection and had returned to its active con- 

 dition. Immunity was thus produced against a virulent culture in 

 guinea-pigs from the same source, namely, milk. 



From these five experiments it is evident that immunity can 

 be produced by the injection of avirulent cultures or sublethal 

 doses of virulent organisms. 



XIII. EFFECT OF FEEDING CLOSTRIDIUM WELCHII 



Previous investigators have met with little or no success by 

 feeding Clostridium Welchii to animals. In a few cases diarrhea 

 has been induced in young guinea-pigs and kittens but attempts 

 to cause ill effects in adult animals have met with negative results. 

 Before determining the effect of feeding cultures to guinea-pigs, 

 feces from several animals were collected and tested for the pres- 

 ence of spores and vegetative forms of Clostridium Welchii. 

 The feces from guinea-pigs, weighing approximately 400 grams, 

 were collected in the following manner. The sides and belly of 

 the pig were washed with a 5 per cent carbolic acid solution and 

 then the pigs were placed in the sterile container one at a time, 

 and a sample of feces collected. After each sample was taken, 

 the container was thoroughly sterilized. After a sufficient 

 quantity of feces had been excreted the pig was released and the 

 feces analyzed as'follows: 



The sample of feces was added to 100 cc. of freshly sterilized 

 water and shaken vigorously until the pellets were thoroughly 



