442 CONTAGIOUS PLEUROPNEUMONIA IN CATTLE 



are seen which could be cultivated upon the ordinary culture media. 

 Examination, however, with very good objectives and strong light at 

 a magnification of 1500 to 2000 diameters, show innumerable very 

 small motile and highly refractive points. These are live organisms 

 which, protected against phagocytosis by the collodion sac, 1 have been 

 able to multiply. 



They can also be cultivated outside of the living body, in a special 

 bouillon prepared according to Martin, as follows: Peptone from 

 digested pig's stomach, 5 parts to 100 parts of cattle or rabbit serum. 

 This must be freed from bacteria by filtration through a Pasteur 

 filter, but must not be heated. If this medium is inoculated from 

 collodion sacs and incubated at 37 C. for two or three days it becomes 

 opalescent, and if shaken there is evidence of slight clouding. The 

 highest magnifications show exceedingly minute highly refractive 

 granules, so small that no conclusions as to their shape can be drawn. 

 These cultures are, however, virulent and they can also be used for 

 immunizing inoculations. Solid culture media can be prepared by 

 adding sterile melted gelatin to Martin's liquid medium. If a drop 

 of pulmonary exudate or of fluid culture is allowed to run over the 

 surface of the gelatin a large number of very delicate transparent 

 colonies can be seen after three or four days with the aid of a micros- 

 cope. A little later the colonies become denser and opaque in the centre. 

 They finally cover the surface with a veil which adheres so firmly that 

 it can only be removed by breaking up the culture medium. If the 

 albuminous exudate or a culture in Martin's liquid medium is filtered 

 through a Chamberland or Berkefeld filter a sterile fluid is obtained; 

 if, however, the fluids are diluted with a watery liquid the microbes 

 pass through. The latter fluid is fully virulent. The organism is 

 aerobic; it does not multiply in vacua or in inert gases; the growth is 

 always slow and scanty, and its optimum temperature is at 36 to 38 C. 

 The microbe takes the basic aniline stains, but it is so small that 

 even after prolonged staining with strong solutions the shape cannot 

 be ascertained and the fine colored dusty particles which are seen 

 are apparently each composed of numerous individual microbes. If 

 impression preparations are made the mass on the cover-glass takes 

 the stain. It is decolorized if treated by Gram's method. 



Animals Susceptible. Cattle, buffaloes, yak, and bison are the only 

 susceptible animals. Natural infection occurs by close contact 

 between cattle. While there is some evidence that infection occurs 



1 The fluid to be inoculated into collodion sacs is obtained in the following manner (Nocard): 

 It is necessary to procure a lung from an animal in an early stage of the acute form of the 

 disease. A place is selected which indicates a consolidation and a collection of fluid behind 

 the pleura. The latter is then superficially cauterized with a hot knife or steel spatula. A fine 

 pointed, sterile, glass pipette is pushed through the cauterized pleura into the layers of the 

 tissue next to it, and about 0.5 c.c. of the clear amber-colored fluid may be so obtained. From 

 this collodion sacs containing sterile bouillon are inoculated, and these after having been 

 sealed at the glass end are implanted into the peritoneal cavity of rabbits. Martin's medium 

 may also be inoculated from the amber fluid obtained by puncture of the pleura. 



