54 Veterinary Medicine. 



ogenes — and rod forms — Bacillus pyogenes). These or other bac- 

 teria are found in the pus of acute abscesses, and when absent in 

 chronic abscesses are to be considered as having perished since 

 the abscess was recent and active. Inoculation of a rabbit with 

 an excess of the pus of an acute abscess produces general puru- 

 lent infection (pyaemia) and early death ; from a medium dose an 

 abscess is produced ; while from a small dose there is no effect 

 whatever. In the latter case the bacteria are overcome and de- 

 voured by the abundance of vitally potent white blood-globules 

 and tissue cells. This pus-forming action of these bacteria ex- 

 plains the great difference in results in wounds exposed to the air 

 and those in the interior of the body and far removed from air and 

 its floating bacteria. A broken bone, with no wound in the skin 

 and little injury to parts around the- fracture, is readily repaired 

 without any formation of pus, if merely kept still and immova- 

 ble ; whereas a broken bone, continuous with a wound through 

 the skin, always tends to form pus or become otherwise infected, 

 and is extremely dangerous even to life. The tendency of every 

 open sore is to form pus on its surface but this may be arrested 

 and avoided by preventing the access of germs, or by a free 

 use of disinfectants aiid a covering which shall arrest and filter 

 out the germs. Similarly in an abscess, evacuation followed by 

 the injection of disinfectants, without the formation of any per- 

 ceptible permanent opening to the outer air, will put a stop to the 

 pus-formation. The subjection of an inflamed part to the control 

 of tliese pus-forming bacteria is dependent on the lowered vitality 

 and power of resistance of the inflamed tissues, and of the white 

 cells of their circulating blood.' Healthy parts can successfully 

 resist them, though they are constantly present in surrounding 

 air and on objects, but in this as in all other cases, of bacterial 

 infection, so soon as the tissue is injured, inflamed and lowered 

 in its power of vital resistance, the pyogenic bacteria assail it suc- 

 cessfully. Hence, too, the more abundant exudations of lymph, 

 the centres of which are farthest removed from the healthy tissues 

 and from nourishment, are the most prone to suppuration. That 

 the germs can make their way to such deep-seated exudations in 

 the substance of solid tissues is to be accounted for by their grad- 

 ual advance through the inflamed and weakened structures from 

 the adjacent skin or mucous membrane, or in some instances by 



