Pathogenesis Lesions 659 



Colonies. The colonies which develop upon the surface 

 of gelatin kept under anaerobic conditions appear to the 

 naked eye as small shining bodies with liquid, grayish-white 

 contents. Under the microscope they appear filled with a 

 tangled mass of long filaments which under a high power ex- 

 hibit active movement. The edges of the colony have a 

 fringed appearance, much like the colonies of the hay or 

 potato bacillus. 



In gelatin tube cultures the characteristic growth cannot 

 be observed in a puncture, because of the air which remains 

 in the path of the wire, unless the tube be placed under anae- 

 robic conditions. The best preparation, therefore, is made 

 by heating the gelatin to expel any air it may contain, in- 

 oculating' it while still liquid, and solidifying it in cold (iced) 

 water. In such a tube the bacilli develop in globular cir- 

 cumscribed areas of cloudy liquefaction (Fig. 198), which 

 contain a small amount of gas. In gelatin to which a little 

 grape-sugar has been added the gas-production is marked. 

 The gas is partly inflammable, partly not. A distinct odor 

 accompanies the gas-production, and is especially noticeable 

 in agar-agar cultures. 



Metabolic Products. Of the toxic products of the organ- 

 ism nothing definite is known. It decomposes albumin, form- 

 ing fatty acids, leucin, hydroparacu marie acid, and an oil 

 with an offensive odor. Among the gases formed carbonic 

 acid, hydrogen, and marsh gas have been detected. 



Pathogenesis. When introduced beneath the skin, the 

 bacillus is pathogenic for a large number of animals mice, 

 guinea-pigs, rabbits, horses, dogs, sheep, goats, pigs, calves, 

 chickens, and pigeons. Cattle seem to be immune. 



Giinther points out that the simple inoculation of the 

 bacillus upon an abraded surface is insufficient to produce 

 infection, because the presence of oxygen is detrimental to 

 its growth. When the bacilli are deeply introduced beneath 

 the skin, infection occurs. 



Mice, guinea-pigs, and rabbits sicken and die in about forty- 

 eight hours. 



Lesions. In the blood the bacilli are few because of the 

 loosely combined oxygen it contains. The great majority 

 of the bacilli occupy the subcutaneous tissue, where very 

 little qxygen is present and the conditions of growth are 

 good. The autopsy shows a marked subcutaneous edema 

 containing immense numbers of the bacilli. If the animal 



