PRINCIPLES OF VETERINARY SURGERY 257 



the accident is extremely rare, this cause of infection may 

 be ignored entirely. Bacteria in health, or even in the 

 earlier stages of disease, are never found floating abun- 

 dantly in the circulation, as was once supposed. The 

 healthy body destroys them. They are found in the dis- 

 eased faci, in the blood of the animal dying from certain 

 infectious diseases, and in the carcass, but not in the cir- 

 culating blood of the comparatively healthy animal. 



The technique of an aseptic operation is based upon 

 the foregoing five well-known and well proven facts.' The 

 pathogenic powers of bacteria, their wide diffusion, and 

 their great viability, necessitate the adoption of a rather 

 complicated technique to prevent their invasion: int& the 

 surgical wound. If the pathogenic powers were trivial, if the 

 bacteria were few and if they were easily killed, aseptic pre- 

 cautions would hardly be necessary. But owing to the fact 

 that very serious, very fatal or very harmful complications 

 result from bacteria, and that almost everything around a 

 surgical operation harbors them, and finally that they are 

 very tenacious agents to destroy, the aseptic techniqiie 

 becomes an absolute necessity. -^It is standard, it is ex- 

 pected, it is malpractice to ignore it.^ 



The aseptic surgical operation begins, therefore, by 

 sterilizing or rendering harmless, all objects that will come 

 into direct contact with the wound. The conveyors of in- 

 fection are' (i) Air; (2) the surgical instruments; (3) the 

 hands of the surgeon; (4) the environs of the wound; (5) 

 the sutures; (6) the antiseptics and the containers of the 

 antiseptics; (7) the surgical dressings; (8) the patient's 

 habitat — the stall, kennel or sty; and (9) the litter. ,,:, ;is 



I. The Air. — As stated above, Lister placed entirely 156 

 much importance on the air as a conveyor of infection. He 

 supposed that myriads of "unknown poisonous bodies" fell 

 upoii the wound as the operation proceeded, and recom- 



