NEW METHOD OF PREVENTING CONTAGION. 31 



lost the use of its legs. It seemed perfectly well when killed, 15 

 days after inoculation. It was quite fat, the crop filled with 

 food. In the pectorals were found imbedded two elongated 

 masses of dead tissue or sequestra about 2 cm. long and i cm. in 

 diameter, entirely separated from the surrounding tissue by a 

 dense, smooth membrane. In this animal the multiplication of 

 the pathogenic bacteria was purely local, the resistance of the 

 tissues being sufficiently powerful to confine, and finally destroy, 

 the bacteria. The sequestra were made up of dead muscular fi 

 bre, which was pale and parboiled in appearance. Each was en 

 veloped by a more or less hyaline homogeneous layer. A liquid 

 culture, inoculated with blood from the heart, remained sterile. 



This experiment pointed evidently to an immunity obtained 

 from the chemical products of the bacterium of swine plague. 

 To confirm this view another experiment was made. 



January 21, three pigeons (Nos. n, 12, 13) received hypo- 

 dermically 1.5 cc. of heated culture liquid in which the bacterium 

 of swine plague had multiplied for two weeks, and was then 

 destroyed by exposure to 58-6o C. for several hours. A fourth 

 pigeon (No. 14) was kept as a check. No. 10, which had re 

 ceived .4 cc. of heated virus Dec. 24, now received a second 

 dose, this time of 1.5 cc. For the following three or four days 

 all were somewhat ill, and remained rather quiet, with feathers 

 slightly ruffled. 



January 29, when all seemed well, three of the four (Nos. 10, 

 n, and 12) received hypodermically another dose of 1.5 cc. of 

 heated culture liquid. The other (No. 13) had been fiercely 

 attacked by its fellows, and its head was so injured that it was 

 thought best not to give it an injection at this time, and it was 

 placed in a spacious coop alone. None of the birds seemed much 

 affected by this dose. 



February 6, a final injection was practised upon the four, No. 

 13 having recovered from the effects of its injuries. The dose 

 was, as before, 1.5 cc. All seemed well a few days later. 



