HEALING OF EXTERNAL WOUNDS. 
411 
In a day or two these germs in presence of excellent nutri¬ 
tion, proper temperature and moisture multiply with the for¬ 
mation of pus and the exudate softens and gives way. Imme¬ 
diate union is impossible. Adhesion may be sufficiently firm to 
require no bandage to keep the parts in apposition, but it is 
not healing. 
The writer is convinced that plastic adhesion has taken 
place in wounds which have been said to have “healed in a few 
hours,” or even in a “ day or two ” and not healing. This ad¬ 
hesion aids the reparative process by holding the edges of the 
wound in close apposition, preventing motion of these edges on 
each' other and excluding foreign materials. The presence of 
any foreign material will prevent healing by primary union, 
because it becomes an irritant, setting up increased inflamma¬ 
tion with its attendant phenomena of emigration of leucocytes 
and formation of pus. Even extravasated blood, if in apprecia¬ 
ble quantities, becomes a foreign body and an irritant and fur¬ 
nishes a medium for the propagation of bacteria. In no in¬ 
stance is it possible for this extravasated blood to assist in the 
process of repair and it is a common mistake for veterinary 
surgeons to bind up a wound before haemorrhage ceases. The 
blood, too, may form a clot in the wound, prevent all possible 
contact of opposing edges and thus give a cavity which later 
must be filled by granulation. 
When a small, aseptic, incised wound is closed by sutures 
an exudate takes place from the suture openings. This is be¬ 
cause the sutures have made a small, open wound with destruc¬ 
tion of more or less tissue. It is nicely illustrated by a neat 
operation of plantar-neurectomy. If the injury is very slight 
new cells are soon formed to replace those destroyed, with little 
or no change in structure, and is the nearest possible approach 
to immediate union. In this case, the earliest signs of prolifer¬ 
ation may be seen in about eight hours after infliction of the 
injury, and very readily seen after twenty-four to forty-eight 
hours. In wounds of a somewhat larger size there is infiltra¬ 
tion of the surrounding tissues, exudate upon the cut surface, 
