270 OF DISEASE GENERALLY. 



the framework of the whole carcass is known to exist in 

 two separate conditions. Diseases, however, vary in ap- 

 pearance according to the part attacked : thus phrenitis is 

 the consequence of morbid vascular action of the brain, and 

 enteritis depends upon the like state within the substance of 

 the intestines ; but phrenitis and enteritis are diseases very 

 dissimilar in their symptoms. Each disease, moreover, is 

 liable to individual peculiarities dependent on the immediate 

 state, age, and temperament of the object attacked. 



The systematic division of diseases is termed nosology, 

 the simplest arrangement of which is the alphabetical. 

 Anciently, diseases w^ere divided according to their dura- 

 tion, and this laid the foundation for the acute and the 

 chrome ; but which subjected the founders to call in the aid 

 of the subacute, for those which ranged in the intermediate 

 spaces. It has also been attempted to arrange diseases 

 simply according to the parts of the animal frame ; which 

 suits well with the plan of uniting the anatomical, physio- 

 logical, and pathological considerations together. At the 

 present time there is an evident disposition to disregard all 

 systematic or arbitrary arrangement of natural causes and 

 effects. Men are now rather inclined to view each disease 

 as a perfect whole in itself, which, though connected with 

 the affections of other structures, is not necessarily joined 

 to one more than to another. Any system, however, which 

 may serve to smooth the path of the student is so far of 

 service but no further. 



The division of diseases into epidemic, endemic, sporadic, 

 and specific, is still acknowledged. Epidemic diseases are 

 such as prevail generally at a particular time among all ages 

 and kinds of our domestic breeds of animals, spreading as 

 though they were imbibed with the air. Of this form of 

 disease the affection so lately fatal among cows is an in- 

 stance ; as the foot lameness which attacks our cows, sheep, 

 and pigs is also an example. Endem ic diseases are those which 

 confine their attacks to a certain locality ; as the glanders, 

 which was confined to certain badly ventilated stables, sadly 

 illustrates. Sporadic diseases stand in opposition to the 

 two former, and are a very extensive class, comprehending 

 all such as affect particular constitutions or ages : thus 

 strangles becomes a sporadic disease. Specific diseases are 



