634 



REPORT OP THE COMMISSIONER OP AGRICULTURE. 



had been multiplying for sixteen, eleven, and fourteen days, respect- 

 ively, Tliree additional pigeons received only two doses from cult- 

 ures sixteen and fourteen days old, respectively. The culture liquid 

 used was beef infusion containing 1 jjer cent, peptone. The tubes de- 

 scribed in the First Annual Report of the Bureau were used unless oth- 

 erwise stated. The liquid was injected beneath the skin covering the 

 pectorals on both sides of the keel. Three pigeons were reserved as 

 a check ujion the experiment. All heated cultures used were tested 

 by inoculating fresh tubes, which remained invariably sterile. Six 

 days after the last inoculation with heated virus the nine pigeons 

 were inoculated each with ^^"^ of the eighth culture, two days old, from 

 the spleen of pig 'No. 156. On the following day two of the three check 

 pigeons were found dead. The rest were apparently undisturbed. The 

 third check pigeon, which was not affected by the inoculation, differed 

 from the rest of the pigeons in having a differently shaped trunk, a 

 long curved beak, large rufffed masses over the nostrils, and nearly 

 invisible iris. It was snow white. It was supposed to have some of 

 the characters of the carrier pigeon. Leaving this bird out of account, 

 this experiment was as conclusive as the preceding in demonstrating 

 the protective power of devitalized cultures. 



In the tv/o dead pigeons the pectorals presented a parboiled ap- 

 pearance over an area about 2"" by 3"" (1 hj 14- inches). On section 

 the discoloration extended into the muscular tissue for from i to ^ 

 inch. Nothing characteristic in the internal organs. In both the 

 oesophagus was filled as far as the pharynx with regurgitated food. 

 This phenomenon had been observed in former cases. 



Since the product formed during the growth of the bacteria is not 

 destroyed by the heat necessary to destroy the life of the bacteria 

 themselves, it became necessary to determine whether the evapora- 

 tion of the culture liquid in a water bath at the temperature of boil- 

 ing water would destroy this product. 



Recent investigations point to an alkaloid or ptomaine resulting 

 from the multiplication of bacteria in liquids. It seemed advisable, 

 therefore, to determine whether the substance producing immunity 

 in pigeons was related to or identical with the rftomaines thus far 

 examined. If the boiling temperature destroyed the power of pro- 

 ducing immunity, the substance possessing this property must either 

 be easily volatile or decomposed at this temperature. The cultures 

 used were renewed from day to day, so that the seventh culture would 



