=Predisposing Causes= are such as induce a condition of the system or of a particular organ or group of organs which renders them specially susceptible to a disease. This may be a characteristic of the _race_ or _genus_ of animal, thus the genus bovis alone suffers from lung plague, the genus equus from dourine, and ruminants from Rinderpest. It may be a _family trait_, (_hereditary_) hence we see certain families of both men and cattle cut off by tuberculosis, while other adjacent ones largely escape. It may be an _individual peculiarity_, thus some subjects have a congenital insusceptibility to a given disease, from which others of the same family suffer, and one who has passed through a self-limiting disease like measles, cowpox or anthrax is rarely attacked a second time. Again predisposition may be due to _environment_ as when we find herds in damp and exposed localities obnoxious to rheumatism, and horses in dark mines exposed to specific ophthalmia. It may be the result of _food_ as when the flesh-fed fox or rat resists anthrax and the farina-fed one falls a ready victim. _Age_ may predispose, early youth being remarkably susceptible to parasitism and bacteridian infection, and old age to fractures and degenerations. _Sex_ is inevitably a cause of limitation of disease as the females and males can only suffer from disease of their respective =sexual= organs. Again of diseases common to both sexes certain nervous and digestive disorders are common in connection with gestation, and certain calculous diseases in connection with the long and narrow urethra of the male. _Temperament_ has a marked influence, thus the sanguineous or nervous race horse or hound shows a marked predisposition to diseases of the heart, lungs and brain, and to a sthenic type of inflammation and fever, while the heavy lymphatic draught horse has a proclivity to diseases of the lymphatics and skin. _Idiosyncrasy_ is closely allied to temperament, but the condition may be less manifest, and the peculiarity is only recognized by the results, as when a man is poisoned by sound fish or raspberries. _Debility_ whether from deficiency or poor quality of food, on the one hand, or from overwork, filth, dampness or disease on the other must be looked upon as strongly predisposing to certain diseases, such as tuberculosis and glanders. _Plethora_ which charges the blood and tissues in a different way with effete organic products, lays the system especially open to certain diseases like black quarter in young cattle, and parturition fever in cows. _Disease of one organ_ often predisposes another organ through interdependence of function, as when torpid or congested liver leads to portal and intestinal congestion, diseased teeth to digestive disorder, imperfect hæmatosis to kidney trouble; in other cases blood clots or bacteria from one pathological centre may be arrested in the blood vessels of a distant organ and start new foci of