30 BIOLOGICAL SOCIETY OF WASHINGTON. 



products (ptomaines?) formed by the bacteria in their vegetative 

 state, and which are probably dissolved in the culture liquid. 

 The heated cultures used in these experiments were always 

 tested by inoculating fresh tubes therefrom, and, if no growth fol 

 lowed this inoculation, the death of the microbes was considered 

 established. 



It had been previously determined that the subcutaneous in 

 jection of .75 cc. ( T 3 ^ dram) of a liquid culture of the swine 

 plague bacterium containing i% of peptone was invariably fatal, 

 in the majority of pigeons within 24 hours. One half of this 

 dose. was fatal to a few only. 



As a preliminary experiment, four pigeons were inoculated 

 December 24, 1885, with a liquid culture that had been heated 

 for 2 hours at 58-6o C. Three of these (Nos. 10, 8, 9) re 

 ceived subcutaneously .4, .8, and 1.5 cc. of the heated culture, 

 respectively. The fourth (No. 7) received 1.5 cc. of the pure 

 culture liquid, into which no microbes had been introduced. 

 No. 9, the one which had received the largest dose, was evidently 

 sick the next day, but slowly recovered. The others did not 

 show any symptoms of illness. 



January n, the one which had received a hypodermic injec 

 tion of the simple culture liquid (No. 7), and the one which had 

 received the largest dose of heated virus (No. 9), received sub 

 cutaneously about .75 cc. each of a liquid culture five days old, 

 which had been prepared from a potato culture 15 days old. It 

 is probable that this virus was not so strong, therefore, as a more 

 recent culture from the pig would have been. Both pigeons were 

 sick on the following day. No. 7 died seven days after inoculation. 

 The bacterium of swine plague was found abundantly in the pec 

 toral muscle, in the spleen, kidneys, and liver in moderate num 

 bers.* The other pigeon (No. 9) slowly recovered, but had 



*In this animal the major part of both pectoral muscles appeared as if 

 they had been boiled; they were whitish, bloodless; the fibres could be 

 easily broken and crushed with the forceps. The muscular tissue sur 

 rounding the dead portion was very dark, gorged with blood. The liver 

 was dark in patches ; spleen and kidney pale. 



