TEXT-BOOK OF B.XTBKIOLOGY. 255 



of such a culture applied subcutaneously to a susceptible animal 

 suifices to produce genuine glanders with all its peculiar symptoms. 



It was natural that we should at first employ horses and asses 

 for these experiments, since their susceptibility to the disease was 

 already known ; but afterward Loffler made the discovery that field- 

 mice and Guinea-pigs were almost equally susceptible, while white 

 mice, the common house mice, cattle, and swine were almost com- 

 pletely exempt. Rabbits were found little susceptible, but cats 

 were very easy to infect. A few drops of a culture well mixed with 

 sterilized water, and put into a pouch in the abdominal wall of a 

 Guinea-pig or injected mto a field-mouse at the root of the tail, in all 

 cases leads to a fatal termination. 



In these artificial infections the fact is clearly apparent that 

 the virus of glanders at first confines itself still more markedly 

 than that of the tuberculosis to local action, and that it only pro- 

 ceeds gradually to spread its fatal influence more extensively. At 

 the spot where inoculation took place the first changes are to be 

 seen, and from there the poison creeps slowly on. But the spread 

 of the affection is only step by step, not by way of the circulation, 

 as the blood is almost always free from bacilli. 



Thus in the case of Guinea-pigs the local symptoms of infection 

 appear four or five days after the inoculation, but as many weeks 

 generally elapse before the general sj'mptoms appear and the 

 death of the animal ensues. The same applies to the horse, but the 

 field-mouse forms an exception, inasmuch as the size of the animal 

 is such as scarcely to admit of a distinction between the local and 

 the general symptoms. Mice, therefore,, generally die on the third 

 or fourth day after inoculation, sometimes still earlier, and in them 

 the whole course of the disease differs from that observed in 

 Guinea-pigs. 



The latter show as the first result of the inoculation a sharply- 

 defined swelling. This gradually becomes caseous, round, or oval- 

 shaped, purulent ulcers with indurated edges develop, and occasion- 

 ally, after many weeks, a cessation of the processes ensues, healing 

 follows, the ulcers leaving deep scars. 



As a rule, however, the local affection is followed by a diffuse 

 swelling of the glands, which leads to suppuration and a purulent 

 discharge. In male animals the testicles thicken into hard nodular 

 masses, which then also fall a prey to suppuration. Lastly, in addi- 

 tion to the other symptoms, comes a diffuse inflammation of the 

 joints, especially of the feet, and death follows from general ex- 

 haustion. It is but seldom that the nasal cavity is attacked. 



In mice, on the other hand, the local symptoms are not noticea- 



