44 Veterinary Medicine. 



in the supposed existence of stigmata (openings) in the vascular 

 walls (Arnold), in the effect of the blood pressure within the in- 

 flamed vessels, in softening of the vascular walls and, in the con- 

 tractility of the leucocyte which is strongly attracted by the 

 presence of certain bacteria and other irritants (chemiotaxis). 

 The migrated leucocyte assumes in the tissues the same habit as 

 the altered tissue nucleus. It multiplies rapidly, assists in the 

 solution and removal of the inflamed tissue, contests the ground 

 with infective microbes (phagocytosis), and subserves the pur- 

 pose of assisting in building up new tissue, or of degenerations. 



Red Cells. The red blood globules follow the active current 

 in the centre of the blood vessel, yet a few of these also become 

 adherent to the softened walls and pass through them (diapede- 

 sis). When stasis of blood takes place in the vessels, they be- 

 come packed more closely with red globules which then pass out- 

 ward into the tissues in much larger numbers. 



Changes in innervation. As shown under hyperasmia the 

 vaso-motor system of nerves exerts a potent influence on the cir- 

 culation and is largely instrumental in bringing about circulatory 

 disorders. The increase in the number and force of the contrac- 

 tions of the heart, and the rigid contraction of the walls of the 

 arteries proceeding to an inflamed part, are distinctly the result 

 of a reflex nervous action. The implication of the second eye 

 when one has been violently inflamed from a mechanical injury 

 is another example of this kind. The loss of power of the vaso- 

 motor nerves is, however, even more characteristic. Experi- 

 mentally the cutting of the cervical sympathetic or crushing of 

 the superior cervical ganglion causes congestion and finally in- 

 flammation of the structures on that side of the head ; the crush- 

 ing of the semi-lunar ganglion similarly affects the abdominal 

 viscera ; and the cutting of the pelvic plexus, the structures of 

 the hind leg. The contraction and dilatation of the inflamed 

 capillaries is largely a nervous phenomenon. A certain number 

 of irritants, like warm water, mustard, or ammonia cause con- 

 traction, followed by dilatation of the capillaries, while others 

 like dilute mineral acids, alkalies, chloroform, or sodium chloride 

 and sugar in concentrated solution produce dilatation at once. 

 Some poisons act variously on different parts, eucalyptol causing 

 dilatation of the arteries and contraction of the veins, while cor- 



