120 



PRINCIPLES OF VETERINARY SURGERY 



is a common inhabitant of pus from most any source. In the 

 more grave suppurations of the domestic animals it is 

 usually associated with other pyogenic micro-organisms. 

 The poll-evil, the quittor, the fistula of the withers, etc., con- 

 tain them either alone or mixed with the staphylococci. In 

 these cases they are the determining causes. When the re- 

 sisting forces of the body are depressed or the infections ex- 

 tremely virulent and abundant, fatal septicaemia or pyaemia 

 are the certain terminations. At autopsies on animals hav- 

 ing died from generalization of septic infections, the strepto- 



FiG. 7a. 

 Streptococcus Pyogenes from Pus. 



coccus is found in the organs in a larger percentage of 

 cases than any of the other pyogenic agents. It is often 

 associated with the septic vibrion, the bacillus of Nicolaier, 

 the bacillus coli communis, the bacillus anthracis, etc., in the 

 lesions of the diseases each of these specific micro-organisms 

 is capable of producing. Inoculative experiments with vir- 

 ulent cultures usually prove fatal to cavies, rabbits, mice, 

 etc. 



Resistance and Virulence. — It is probably more virulent 

 in man than in animals. Animals suffering from puerperal 

 infection caused by streptococcus often get well, while in the 



