172 THE VASCULAR SYSTEM 



in the regeneration of feathers after moult. The procreative and 

 reproductive functions too are accompanied by active hyperaemia. 

 Hyperaemia is the natural reaction of the tissues to injury, foreign 

 material and bacterial invasion, and this hyperaemia is not to 

 be combated, but regarded as the natural healing agent. Anti- 

 phlogistic treatment, says Bier, may relieve the pain, but it retards 

 the healing process, and may render it less complete. The treat- 

 ment of Bier and of A. Wright is to promote the flow of plasma 

 into the infected or inflamed tissues. Venous congestion or cupping 

 are the methods employed by Bier. 



The knife of the surgeon employed in the opening of ab- 

 scesses, &c., has the same influence in relieving tension and allow- 

 ing the free transudation of plasma. Wright employs sodium 

 citrate solutions as a drug or locally as an irrigant to lessen coagu- 

 lability and thus increase the permeation of the infected part. 

 Chronic disease is chronic because the bacterial excitant does not 

 provoke an active hyperaemia ; make this appear and healing 

 follows. Animals infected with anthrax and streptococci have been 

 protected by the induction of venous congestion in the infected 

 part owing to the intensified " antitropic " action of the plasma. 

 The defence lies in the plasma, and hence while blood infection is 

 rare local infection is of e very-day occurrence. The plasma is 

 turned on to the infected local area in full stream, and if nature 

 fails to do this, the surgeon must aid the transudation. Salt 

 rubbed into wounds of slaves after whipping by osmotic force has 

 this effect, while hot fomentations produce hyperaemia and soften 

 the skin and so allow more transudation. 



Resorption is favoured by the hyperaemia which follows venous 

 congestion, especially if massage be employed. Potassium ferro- 

 cyanide solution, introduced into a joint, appears thirty minutes 

 later in the urine. When hyperaemia of that joint is induced the 

 salt appears in the urine in six to ten minutes. Lactose is a good 

 test substance to inject because its presence in the urine can be 

 detected by the polarimeter. The resorption of this is doubled or 

 more in rate by exposure of the animal to hot air and made very 

 slow by packing the limb in ice. When two limbs of an animal, 

 with the bones fractured, are splinted, and "one limb surrounded 

 with an air bath at 38 C. and the other at 10 C., a callus forms 

 in six to seven days in the limb which is kept warm, while the re- 

 generative process has just begun in the other. Hence the curative 



