CHANGES IN THE BLOOD, 93 



It has been maintained by some writers that urea is a product 

 formed in the kidneys, and by others that it is an oxidized 

 albuminous material, due to the degradation of muscular tissue, 

 brought about by muscular exertion only, and merely excreted 

 by the kidneys. 



Without a doubt urea is an oxidized or degenerated condition 

 of albumen, but the occurrence of the immense quantity of it in 

 conditions of the animal body opposed to that of tissue change, 

 I think, disposes of the idea that urea is due only to metamor- 

 phosis of tissue, and supports the theory that it is formed in the 

 blood itself, or in the liver, as advocated by Meissner. 



The rules for the proper treatment of disease depending on 

 blood loaded with effete materials are — 1st. To clear the intestinal 

 canal of the materials with which it may be loaded, and from 

 which additional matter may be absorbed and conveyed to the 

 blood: 2d. To stimulate the powers of the excretory organs, 

 kidneys, and skin: and 2d. To attend to the comfort of the 

 patient, and particularly to supply it with abundance of water, 

 which not only allays the thirst, but dilutes the blood and 

 stimulates excretion. 



MELLIT^MIA. 



The sugar in the blood is increased in certain diseased 

 conditions — diabetes mellitus and in some cases of azoturia 

 in the horse. It is then partly excreted by the kidneys. 

 True diabetes mellitus is but rarely witnessed in horses, 

 and perhaps never in cattle and sheep, but is not uncom- 

 mon in dogs ; and to replace the loss of sugar thus given 

 there is an increased metabolism of the nitrogenous structures, 

 and consequently the amount of urea is increased. There is 

 loss of flesh, the glands atrophy, and the crystalline lens becomes 

 opaque, and there being an increased amount of sugar in the 

 humors of the eye, the water of the lens is extracted (Osmosis). 



