IN SUSCEPTIBLE ANIMALS. 



519 



This bacillus grows as well in an acid medium as in one which is slightly 

 alkaline. In gelatin plates, at the end of eighteen to twenty-four hours, 

 colonies are formed which under a low power are seen to be spherical and 

 to contain a quantity of shining granules ; the following day, at a tempera- 

 ture of 15 to 17 C., the colonies may be as large as a pin's head and still 

 remain spnerical or slightly oval, but 

 the outline is no longer so uniform, 

 and between the shining points in the 

 interior a confused network may be 

 seen ; as the colony becomes larger it 

 is raised above the surface of the gela- 

 tin, becomes opaque, and has a pearly 

 lustre like that of Friedlander's bacil- 

 lus. In gelatin stab cultures the 

 growth resembles that of Friedlan- 

 der's bacillus " nail-shaped growth." 

 Upon the surface of nutrient agar a 

 rapidly extending, semi transparent 

 layer is formed. Upon potato, at 15 ' 

 to 17 C., at the end of twenty-four 

 hours transparent drops are seen in 

 the vicinity of the point of inocala- 

 tion, and later a moist, shining, color- 

 less layer, of tough consistence, is 

 formed, which gradually extends over 



the surface. The growth upon blood 

 serum resembles that upon nutrient 

 agar, and the blood serum is not liquefied. 



Pia. 140. Proteus hominis capsulatus, from 

 liver of mouse. X 1,000. (Bordoni-Uffre^ 

 duzzi.) 



IMSL ti , K/IJ.VI. vi*.\j ^ n.*~r-~r-~~ -^-^.^ . *-^. . ~ . ^ ~. . i liquid Diood serum or in. 



bouillon the bacilli are isolated not in filaments; they cause a clouding of 

 the liquid, and an abundant deposit accumulates at the bottom of the tube, 

 while a film of bacilli forms upon the surface. The cultures never give off 

 a putrefactive odor. 



Pathogenesis. Pathogenic for dogs and for mice, less so for rabbits and 

 for guinea-pigs. Agar cultures grown in the incubating oven at 32 to 37 

 G. are more pathogenic than cultures in gelatin at the room temperature. 

 A small quantity of a recent culture injected subcutaneously in mice cause* 

 their death in from one to four days, according to the quantity and age of 

 the culture; the recent cultures are most virulent. When the animal lives 

 more than twenty -four hours it has a mucous diarrhoea. At the autopsy the 

 spleen is found to be much enlarged and dark in color ; the lymphatic 

 glands are also swollen and haemorrhagic, the liver and kidneys hyperaemic; 

 in the vicinity of the point of inoculation is a subcutaneous oadema of jelly- 

 like appearance and numerous punctiform haemorrhages are seen. The ba- 

 cillus is found in great numbers in the effused serum from the subcutaneous 

 tissues, in the blood, the contents of the intestine, and in the parenchyma of 

 the various organs. When examined at once the bacilli in the subcutaneous 

 oedema and in the lymphatic glands are usually quite short, and even spherical, 

 while in the blood they are somewhat longer and may appear as short fila- 

 ments with swollen ends, surrounded by a capsule. When the examination 

 is made some time after the death of the animal longer filaments are quite 

 numerous. Rabbits and guinea-pigs are killed by the intravenous injection 

 of comparatively small amounts of a recent culture, but quite large doses 

 are required to produce a fatal result when the injection is made beneath 

 the skin. From two to three cubic centimetres of a recent culture injected 

 into the circulation of a dog give rise to symptoms of toxaemia, and the ani- 

 mal usually dies on the second day. At the autopsy the abdominal organs 

 are found to be hyperaemic, the mucous membrane of the intestine swollen, 

 red in color, and covered with bloody mucus. The bacillus is found in the 

 blood and in the various organs. When smaller doses are injected into a 

 vein (a few drops) the animal, after a few hours, has a mucous diarrhoea and 



