150 Manual of Veterinary 31icrohiology. 



cus aureus has led to the discovery of a non-toxic pto- 

 maine, a non-nitrogenous phlogogenic and pyogenic 

 substance called j^hiogosine, and a diastase also pyoge- 

 nic. The yellow coloring matter is only developed in 

 contact with the air. 



Research and coloration. — In order to bring into 

 view the microbes of pus it suffices to stain the latter 

 on cover glasses for a few seconds with -a hydro-alco- 

 holic solution of gentian violet. The Gram reaction, 

 which they all sustain, admits of obtaining double 

 coloration. "We, by this means, see the microbes be- 

 tween, and often even inside, the pus corpusles. 



Etiology. — The germs of pus most frequently pene- 

 trate into the tissues through a solution of continuity, 

 but they may also invade the organism when the 

 skin is intact ; this has been demonstrated by Garre ; 

 frictioning of the arm with a culture of staphylococcus 

 aureus caused, on the same day, the eruption of 

 furuncular pustules. IN'umerous examples of this 

 truth are furnished by veterinary accoucheurs, in 

 whom the arm becomes covered with pustules as a 

 result of their intervention in difficult parturition 

 or in removal of the placenta. In this case the le- 

 sions always develop at a pilo-sebaceous follicle, 

 through the orilice of which the purulent germs have 

 entered. Finally, the germs of pus may gain the 

 tissues by traversing the normal mucosa. 



The pyogenic germs which we have just referred 

 to are not the only ones which can give rise to the 

 formation of pus. A number of others possessing 

 specific virulent properties have, in addition, the 

 power of exciting suppuration ; among these are the 

 Koch bacillus, the bacillus of glanders, the actino- 



