BUREAU OF ANIMAL U:T)VSTRY. 637 



In order to determine wlietlier such very susceptible animals as 

 rabbits and guinea-pigs could be made immune by heated cultures 

 three rabbits were selected, two of which were inoculated with heated 

 cultures and the third kept as a check. The culture liquid used con- 

 sisted of about 2 per cent. Liebig's meat extract and 2.^- per cent, pep- 

 tone, neutralized with sodium carbonate. Contrary to the former 

 method, the cultures were made in Erlenmeyer flasks, and the liquid 

 was not more than 1'''" deep. Considerable evaporation took place 

 through the cotton-wool plug, which was covered with tin-foil. Thus 

 it was presumed the bacteria would multiply more abundantly be- 

 cause of the greater amount of air to which the surface of the liquid 

 was exposed. When the cultures were fourteen days old they were 

 heated to 58° C. to destroy all life, their sterility subsequently being 

 tested by reinoculation into fresh tubes. Rabbits Nos. 3 and 4 re- 

 ceived subcutaneously into the thigh on April 24 and 28 and May 1 

 Lb""" of this culture liquid. May 6 the three rabbits (ISTos. 2, 3, 4) 

 were inoculated subcutaneously with an equivalent of sou'"' ot a four- 

 teenth culture of the bacterium of hog-cholera. Nos. 2 and 3 were 

 found dead May 12. No. 4 died on the morning of the same day. 



All, therefore, succumbed to the inoculation with strong virus in 

 about six days, those having received about 4. 5'''' of the heated cult- 

 ure as quickly as the check animal. 



In No. 2 (check) there was slight necrosis of the muscular tissue at the place of 

 inoculation. Small amount of serum in the peritoneal cavity. Spleen enlarged, 

 very dark, and friable. The bacterium of hog-cholera was present in large num- 

 bers in cover-glass preparations of the spleen and Uver, fewer in kidneys, the cortex 

 and pyramids of which were deeply congested. A liquid culture from the heart was 

 found pure microscopically and when grovrn on gelatine ])lates. 



In rabbit No. 3 local necrosis more pronounced than in No. 2. Ecchymoses on 

 the contiguous wall of the abdomen. Large intestine loosely adherent to bladder, 

 the latter to abdominal wa,ll; mesenteric vessels distended with blood; spleen very 

 soft, dark; bacterium of Jiog-cholera very numerous in spleen, less so in liver. A 

 gelatine tube culture from the spleen pure. 



In No. 4 the local lesion was similar to that in Nos. 2 and 3. The liver studded 

 throughout with very small punctiform or stellate gi-ayish- while masses of coagu- 

 lation necrosis. A large abscess filled with white creamy pus and with a well-de- 

 fined wall fills the major portion of the right lung. Several small abcesses present. 

 The bacteria of hog-cliolera were abundant in spleen and liver. A liquid culture 

 of blood from the heart and a gelatine tube culture from the hver were both pure 

 cultures of the same bacterium. No immunity was thus obtained by the injection 

 of tills quantity of devitahzed culture liquid. 



A sunilar experiment was tried with three guinea pigs, the same cultures being 

 used. Nos. 5 and 6 received subcutaneously into the thigh 1" April 21, 24, and 28. 

 The culture first used ten days old, those used subsequently fourteen days old. May 

 5, one week after the last injection, the tlxree animals were inoculated with an equiv- 

 alent of iTiW^"^ of a thirteenth culture in beef -infusion peptone two days old. The 

 check animal (No. 7) and one inoculated animal (No. 5) both died May 16, eleven 

 days after inoculation with sti'ong virus. They were well and active to within a 

 few days before death, when they began to crouch together and breatlie heavily. In 

 No. 5, at the place of inoculation, two small glands were enlarged, and a cavity was 

 found containing soft, dirty grayish material, sho^ving no cellular structure under 

 the microscope. It was very likely a product of coagulation necrosis. The spleen 

 was enormously enlarged, its dimensions being 2 by 1 by :J inch. The Uver was 

 dotted with grayish points and patches of coagnilation necrosis. Kidneys pale, soft, 

 enlarged. Lungs of a deep red. Both Uver and spleen crowded with hog-cholera 

 bacteria. A gelatine tube culture from the spleen pure. In No. 7 the local lesions 

 were confined to an enlargement of the lymphatics, otherwise the lesions were iden- 

 tical with those of No. 5. One cover-glass preparation from spleen and Uver re- 

 vealed no bacteria, but a hquid culture from heart's blood and a gelatine tube 

 culture from the spleen were both pure. In both rabbits and guinea-pigs the local 

 lesions were more pronounced in those previously moculated vrtth heateii v\mr-. The 

 third guinea-pig remained weU. A second ino'culation with J-'^>= of a licjuid culture 

 May 22 was also without effect, as it was well and active Jime 2. 



