286 CHAPTELi 34A, 



from the blood the special nutrient material which is needed for its own 

 maintenance or repair. Thus, muscle extracts from the blood the 

 material necessary for the maintenance of muscle. Bone extracts the 

 material necessary for the maintenance of bone. Each hair extracts the 

 material needed for the maintenance and growth of hair. 



We cannot explain exactly how the various parts or organs of the 

 body each extracts from the blood its own special nutrient material. 

 But the power to do so is inherent in the tissue or cell element of each 

 part. These are facts which we cannot explain. They are termed Vital 

 processes. These processes are beyond the ken of man. 



Having thus premised that the Body in health is sustained by material 

 drawn from the blood, we now come to the repair of injuries by an 

 increased amount of material drawn from the same source, namely, from 

 the blood. 



570/. Repair of Injuries. 



When an injury takes place, disturbance of the usual vital processes 

 also takes place. Irritation, nervous irritation, is in consequence set up. 



This irritation, though we often do not so recognise it, is the com- 

 mencement of Nature's system of repair. By irritation, more blood is 

 drawn to the part. We cannot exactly explain why this occurs. It 

 is a fact. 



From the presence of more blood, the part becomes hot and perhaps 

 inflamed. 



Still, this is a process of repair. The injury cannot be repaired with- 

 out the presenpe of an abnormal, i. e. greater than usual amount of blood 

 in the part. The usual supply of blood is only sufficient for the main- 

 tenance of the part in health. For the purpose of repair more material 

 is needed, and therefore more blood is needed in the part, from which to 

 extract the reparative material. 



570#. Detail of the Process of Repair. 



By the nervous irritation caused by the injury, more blood is drawn 

 to the part. 



The blood-vessels in the part become overloaded, Nature is unable 

 to pass on this abnormal quantity of blood. The blood-vessels then 

 become distended, and after a time, by over-distension, lose their con- 

 tractile power. Stagnation of the blood and congestion of the vessels in 

 the part then to a certain degree occur. The coats of the blood-vessels 

 become more and more distended, and thereby become thinner. In this 

 stage of congestion and distension, parts of the blood begin to ooze out 

 through the coats of the blood-vessels. This is the material needed for 

 repair. This is Nature's effort at repair. This stage is known as exu- 

 dation. 



Since Nature thus finds the material needed for the repair of the 

 injury, " what need is there of treatment ? " 



