44 PATHOLOGY. 



the temperature of the animal body has now made progress in 

 veterinary medicine, and is considered of great importance as an 

 aid to diagnosis and prognosis. It has been advocated by clini- 

 cal teachers since 1754, when Antonius de Haen, of the Hospital 

 of Vienna, impressed his pupils with the necessity of attending 

 to the temperature of the body in disease, as measured by a ther- 

 mometer, instead of being judged by the hand. He showed that 

 even in the cold stage of ague, with the teeth chattering and the 

 body shivering, the temperature of the blood is rapidly rising, 

 although the paUid skin may be cooler than usual, its supply 

 of blood being diminished by the contraction of its vessels. 



The production of animal heat is due to certain chemical and 

 vital changes, which are continually taking place in the body ; 

 and consist in the absorption of oxygen by the pulmonary 

 capillaries, the combination of that oxygen with the carbon and 

 hydrogen derived from the disintegration of animal tissues, and 

 from certain elements of the food which have not been converted 

 into tissue. This combination of oxygen, or oxidation, not only 

 takes place in the blood, which may be looked upon as a fluid 

 tissue, but in the tissue cells of all parts of the body, the animal 

 heat being thus maintained by the natural changes which are 

 essential to a healthy condition. 



The oxidation and natural decay of the tissues, the process by 

 which they are rendered fluid and fitted for absorption, has 

 been termed the secondary digestion, and is thus described by 

 Bennett : — " Growth having been effected, it is necessary that the 

 particles of the tissues which have fulfilled their function and 

 are worn out should be removed to give place to new ones. 

 This constitutes the so-called secondary digestion, — that is, in the 

 same way that a piece of food, say flesh, is broken down, 

 rendered molecular and fluid, and is absorbed into the blood to 

 add bulk to the frame, so is our own living flesh constantly 

 breaking down, rendered molecular and fluid, and absorbed into 

 the blood, to be finally thrown out of the system. Thus the blood 

 receives matter from two sources, the primary and secondary 

 digestions ; and is continually giving off matter in two directions, 

 one to build up the tissues and form the secretions, the other 

 to produce the excretions." — (Bennett's Clinical Lectures.) 



In many diseases this secondary digestion or metamorphosis 

 of tissues, which is mainly due to their oxidation, is abnormally 



