44 Veterinary Medicine. 



existence of stigmata (openings) in the vascular walls (Arnold), 

 in the effect of the blood pressure within the inflamed vessels, 

 in softening of the vascular walls and, in the contractility of the 

 leucocyte which is strongly attracted by the pressure of certain 

 bacteria and other irritants (chemiotaxis) . The migrated leuco- 

 cyte 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 purpose of assisting in building 

 up new tissue, or of degenerations. 



Red Cells. The red blood globules follow the active current 

 iu 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 hypersemia the 

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

 lation 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-mo- 

 tor nerves is however even more characteristic. Experimentally 

 the cutting of the cervical sympathetic or crushing of the superior 

 cervical ganglion causes congestion and finally inflammation of 

 the structures on that side of the head ; the crushing 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 contraction followed by 

 dilatation of the capillaries, while others like dilute mineral acids, 

 alkalies, chloroform, or sodium chloride and sugar in concen- 

 trated solution produce dilatation at once. Some poisons act vari- 

 ously on different parts, eucalyptol causing dilatation of the arteries 

 and contraction of the veins, while corrosive sublimate causes con- 

 traction of the arteries and dilatation of the veins. 



