IMMUNITY FROM CONTAGIOUS DISEASES. 
65 
issues being sufficiently powerful to confine, and finally destroy 
;he bacteria. The sequestra were made up of dead muscular 
ibre, which was pale and parboiled in appearance. Each was en¬ 
veloped by a more or less hyaline homogeneous layer. A liquid 
nilture, inoculated with blood from the heart, remained sterile. 
This experiment pointed evidently to an immunity obtained 
:rom the chemical products of the bacterium of swine plague. 
To confirm this view another experiment was made. 
January 21, three pigeons (No. 11, 12, 13) received hypo- 
lermieally 1.5 cc. of heated culture liquid in which the bacterium 
1 )f swine plague had multiplied for two weeks, and was then 
lestroyed by exposure to 58°-60° C. for several hours. A fourth 
hgeon (No. 14) was kept as a check. No. 10, which had re¬ 
ceived .4 cc. of heated virus Dec. 24, now received a second 
lose, this time of 1.5 cc. For the following three or four days 
11 were somewhat ill, and remained rather quiet, with feathers 
lightly ruffled. 
January 29, when all seemed well, three of the four (Nos. 10, 
1, and 12) received hypodermically another dose of 1.5 cc. of 
leated culture liquid. The other (No. 13) had been fiercely 
Hacked by its fellows, and its head was so injured that it was 
bought best not to give it an injection at this time, and it was 
)laced in a spacious coop alone. None of the birds seemed much 
effected by this dose. 
February 6, a final injection was practised upon the four, No. 
-3 having recovered from the effects of its injuries. The dose 
vas, as before, 1.5 cc. All seemed well a few days later. 
February 13, one week after the last injection, these birds were 
noculated with strong virus, the quantity injected being .75 cc., 
vhioh had hitherto proved invariably fatal, with the single excep- 
ion of the bird that had been previously treated with heated virus. 
ffiose inoculated were Nos. 10, 11, 12, 13, which had received 
he heated virus, also No. 14, the check pigeon, which had not 
•een touched, and No. 8, which had received a small quantity, 
3 cc. of heated virus, December 24, over 50 days before. 
On the following day the check pigeon (No. 14) was found 
ead; the one which had received the smaller dose (No. 8) 
was 
