PRINCIPLES OF VETERINARY SURGERY 355 



unless the phlegmon is sufficiently intense to provoke excep- 

 tional disorders. The fibrous tissue then changes its char- 

 acter; it becomes leaden, and assumes a characteristic gray 

 or greenish color. The periosteum and the serous membranes 

 offer marked resistance and become thickened. Blood vessels 

 may remain in the midst of a purulent center without ap- 

 preciable alteration for a rather long period, but vi^ill event- 

 ually yield to the dissolving process, and when suppuration 

 persists, their coats may become corroded, completely per- 

 forated, and death may supervene from hemorrhage. 



2. Study of Pus. — The study of pus belongs more partic- 

 ularly to the pathological anatomy of inflammation in gen- 

 eral. 



Pus collected in a vessel after opening of an abscess is 

 a creamy, opaque liquid, varying slightly in color and con- 

 sistency, according to the kind and nature of the suppurating 

 organ. The pus known as "laudable" is a liquid of animal 

 odor, sweetish taste, and of alkaline reaction. That of the 

 mouth and rectum is fetid; that of the parotid region has a 

 repulsive odor; that of the urinary tract has the smell of 

 mice; and that of the mammas the smell of milk. 



In the horse pus is generally yellowish and of a semi- 

 liijuid consistency, while in the bovine species it is thicker. 

 In certain cases it may acquire the consistency of putty, for 

 which reason it may require more time to perforate the skin. 

 In consequence of the thickness of the integument, the se- 

 rum may be absorbed by degrees and leave in the cavity only 

 a thick, doughy product adhering to the pyogenic membrane. 

 In the hog, pus is sometimes colored green, owing to the 

 presence of the bacillus pyocyanus. In the dog, pus collec- 

 tions are frequently mingled with more or less blood, and 

 hence are of a chocolate color. 



In every species pus collected is evidently composed of 

 two parts, like blood and lymph : One part, solid, consisting 



