504 PATHOGENIC AEROBIC BACILLI 



observed, or with the contents of a bubo, or with pieces of internal organs, 

 or even with the contents of the intestine, they begin to become ill in from 

 one to two days, according to the size of the animal. Their eyes become wa- 

 tery, they begin to show disinclination for any effort, later they avoid their 

 food, and hide quietly in a corner of the cage. The temperature rises to 

 41.5 C., and with convulsive symptoms they die in from two to five days. I 

 must observe that in Hong-Kong I could only obtain small guinea-pigs 

 (weight from one hundred to one hundred and fifty grammes) and small 

 rabbits (from two hundred to two hundred and fifty grammes). If I could 

 have experimented upon larger animals it is possible that life would have 

 been prolonged somewhat beyond the periods mentioned above. The parts 

 around the point of inoculation are infiltrated with a reddish gelatinous 

 exudation, the spleen is enlarged, sometimes there is a swelling of the lym- 

 phatic glands, and in all the orsrans the bacilli are found. The results found 

 after death in animals are very similar to those found in anthrax and in 

 oedema malign um. Pigeons do not appear to be susceptible to the influence 

 of the bacilli. I made experiments by feeding some mice and guinea-pigs 

 with pure cultivations of the bacillus and with small pieces of the internal 

 organs : the result was, such animals perished in a few days under the same 

 symptoms as those which had been inoculated. In all the internal organs 

 of animals so destroyed I found the bacilli. With the dust of dwelling- 

 houses from which the plague-stricken had been removed, I made sev- 

 eral experiments upon animals. Some of the animals died from tetanus. 

 In one case only a guinea-pig died with plague symptoms, and in this ani- 

 mal the same bacilli were found in the internal organs as in those of 

 plague patients who had succumbed. These experiments with the dust from 

 infected houses I shall certainly continue. Many rats and mice at present 

 die spontaneously in Hong-Kong. I examined some of them. In the inter- 

 nal organs of a mouse I discovered the same bacilli. 



Experiments with Desiccation, The contents of a bubo in which the 

 bacilli were present in great numbers were wiped over cover glasses (per- 

 fectly cleansed by heat and alcohol), 'and some of these cover-glasses were 

 dried in the air of a room at a temperature ranging from 28 to 30 C. Oth- 

 ers I exposed directly to the sun's rays, and from among them, after an expo- 

 sure of from one, two, and three hours up to six days, I removed some parts, 

 putting such portions in beef-tea and placing them in the incubator. Those 

 which had been standing in the room from one to thirty-six hours showed a 

 pretty good growth in the incubator, but those which had been in the room 

 for more than four days were unable to show any growth even after one 

 week's incubation. Those exposed directly to the sun were all destroyed after 

 from three to four hours. Further cultivations 011 serum were treated 

 exactly like the contents of the bubo with very similar results. 



Experiment* tn'th Heat. Beef -tea cultivations which had been heated 

 for thirty minutes in a water bath up to 80 C. were destroyed: at 100 C., in 

 the vapor apparatus they were destroyed in a few minutes. 



Yersin reports that when fragments of the spleen or liver of 

 animals which have died of the plague are fed to rats and mice they 

 usually become infected and die, and the bacillus is found in their 

 organs, lymphatic glands, and blood. He also demonstrated the pres- 

 ence of the bacilli in dead rats found in the houses or streets of 

 Hong-Kong. 



Without doubt rats play an important part in the propagation of 

 the disease. Monkeys are also very susceptible to infection, and it is 

 said that the disease has been known to occur as an epidemic among 

 these animals. There is also good reason to believe that fleas have 

 some influence in the propagation of the disease, by transferring the 



