522 PATHOGENIC AEROBIC BACILLI 



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

 oedema malignum. 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 on serum were treated 

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



Experiments with 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. 



167. BACILLUS PISCICIDUS AGILIS (Sieber). 



Discovered by Sieber (1895) in infected fish, which died of an epidemic 

 disease in the laboratory of Professor Nencki, at St. Petersburg. 



Morphology. Short bacilli, often united in pairs. 



Biological Characters. An aerobic and facultative anaerobic, motile, 

 liquefying bacillus. In old cultures in bouillon spores are developed. 

 Grows at temperatures of from 12 to 37.5 C. Thermal death point, 00 to 

 65 C. On gelatin and agar plates forms granular, grayish, or yellowish 

 colonies, which appear to be made up of three concentric rings the outer one 

 having a jagged outline. Gas is developed during the growth of the bacillus 

 carbon dioxide and methyl merecaptaii in small amount. Upon potato it 

 f<nns yellowish-brown, pearl -like colonies. Causes coagulation of milk. 

 Retains its vitality and virulence for months in well or river water. 



Pathogenesis. Pathogenic for fish, frogs, guinea-pigs, rabbits, mice, 

 and dogs (not for birds). Old cultures are more pathogenic than recent 

 ones, and gelatin cultures are the most active. Frogs are killed in half an 

 hour by 0.1 cubic centimetre of a bouillon culture six days old. Filtered 

 cultures are as toxic as those containing the living bacillus ; they give with 



