M1CROSPIRA METCHNIKOVL 505 



the spirilla are not found in the blood, but in young 

 ones they are usually present in small numbers. 



After the introduction into the pectoral muscle of a 

 very small quantity of a culture of this organism 

 pigeons succumb in from eight to twenty hours. The 

 most conspicuous post-mortem lesion is found at the site 

 of inoculation. The muscle is marked by yellow, 

 necrotic stripes ; is more or less cedematous ; is swollen, 

 and contains the vibrios in enormous numbers. The 

 intestines are usually filled with fluid contents, which 

 may or may not be blood-stained ; the walls of the in- 

 testines are often injected with blood, and occasionally 

 markedly so. The conditions of the other internal 

 viscera are inconstant. In fatal cases the vibrios are 

 present in large numbers in the blood and internal 

 organs. In pigeons that survive inoculation the organ- 

 isms may be found only at the site of inoculation, or 

 very sparingly in the blood also. These animals usually 

 exhibit immunity from subsequent inoculations. In 

 certain instances the results of infection are chronic; 

 the inoculated pectoral muscle atrophies, the pigeon loses 

 in weight and finally dies after one or two weeks. In 

 these cases the organisms are usually absent from the 

 blood and internal organs, and may even be absent from 

 the site of inoculation, or, if present, in only very small 

 number. 



Guinea-pigs usually die in from twenty to twenty- 

 four hours after subcutaneous inoculation. At autopsy 

 an extensive redema of the subcutaneous tissues about 

 the seat of inoculation is seen, and there is usually 

 a necrotic condition of the tissues in the vicinity of the 

 point of puncture. As the blood and internal organs 

 of both pigeons and guinea-pigs contain the vibrios in 



