PRINCIPLES OF VETERINARY SURGERY 353 



rapidity of their development depends upon the resistance 

 of the tissues of the region where the abscess is growing. 

 Pus collections have a tendency to burst through the skin, 

 or just at its junction with mucous membranes. Explana- 

 tion of this phenomenon has been sought and the most im- 

 probable hypotheses have been advanced. Hunter has com- 

 pared the tendency of pus to direct itself towards the exter- 

 nal surface of the body with the unknown force that guides 

 the feather towards a wave of atmosphere. The pulsating 

 force of the arteries has been relied upon, and researches 

 have been made which tend to demonstrate the fjart played 

 by the blood current in the movement of pus. In reality 

 the exact cause of this phenomenon has yet to be discovered. 

 In certain organs the path taken by the pus can easily be 

 explained. In the cornea, for example, the lamina have a 

 disposition which in a very manifest fashion favors the move- 

 ment of pus towards the surface. In other organs pus obeys 

 the laws of gravity. Its tendency is downward when its 

 course is not governed by muscular movements which can 

 compel it to spread in one direction or another. It is, how- 

 ever, necessary to bear in mind that the different muscles are 

 joined together by connective tissue, — "ce tissu d'union," — ■ 

 as Bichat called it, and that pus has quite a natural tendency 

 to s'ip into the interstices at points where there is the least 

 . resistance. These connective tissue spaces are in more or 

 less close relations with the dense areolar tissue beneath 

 the skin and this favors the collection of pus at that point. 

 The micro-organisms and their diastases then ulcerate an 

 orifice through the skin and the collection empties itself ex- 

 ternally. It is not rare to have purulent eruptions of the 

 withers forming abscesses in the chest. Diseases of the foot 

 are often starting points of abscesses in the pastern, and ab- 

 cesses of a scirrhous cord may burst in the upper inguinal 

 region, etc. 



