=Heredity Plays a Part.=--Despite caution and care, health is often disturbed because of hereditary influences. Thanks to science, we know now that many of the old bugbears of the past, and once so entrenched, have become dislodged, and their true import set right before the owner. Tuberculosis, for instance, once so dreaded in both man and beast, is now known not to be handed down from parent to progeny; it is a germ disease, pure and simple, and gets its start just as many other ailments--through breath, or drink, or feed. There are hereditary troubles, however, that continue down through many generations. The narrow hock of the horse invites curb diseases; the narrow chest is a good breeding ground for tuberculosis germs; straight pasterns are bad for the feet; poor conformation is not consistent with efficiency or easy functional activity. These examples clearly show that form and type and physical characteristics have roles to play in animal economy and in health to which the wise stockman will give heed. [Illustration: BACTERIA AS SEEN UNDER THE MICROSCOPE _a_, Spirillum. _b_, Micrococcus. _c_, Micrococcus. _d_, Streptococcus. _e_, _f_, _g_, _h_, Rod-shaped bacteria. _i_ and _j_, Divisions.] =Germs and Parasites.=--In addition to the above causes of disease, another class is before us ready to inflict its injury at all times. Indeed, it is a class of the greatest importance. I refer now to parasites, bacteria, and germs, which cause more loss to live stock than all others combined. Think of hog cholera, a germ disease; of tuberculosis, a germ disease; of stomach worms, parasites; of staggers, a mold disease; of abortion, a germ disease; and hundreds of like nature, all due to parasites and germs, disease agents that disturb and destroy the delicate organs or exposed regions, as the case may be, regardless of age, value, or breed. Of course, remedies and treatment are being worked out to meet these individual diseases as they occur. Nevertheless, the best treatment is prevention. It is far better to prevent than to cure; and that is the line of action especially for this class. Indeed, it is far easier to understand the simple laws of prevention than the complicated curative processes. Especially is this true since germs are known and isolated, and their rapid destruction with air, sunlight, and disinfectants understood and available. ORIGIN OF DISEASE