_Salt_ in excess, the _brine of salt meats or fish_ (containing toxins), the _powdered soaps_ used in kitchens and added to swill, _mouldy bread, cotton seed meal_ fed in any considerable proportion in the food, and even an exclusive diet of _corn_ (maize), must be guarded against. The crowding of many pigs in a small yard where they root continually in each others’ droppings and their own, should be avoided. Individual pens, or pens holding two or three only and kept clean are to be preferred, and still more a wide grassy range where they may escape from their own filth. The long feeding trough should be discarded in favor of one into which the pig can introduce his nose only. The nose itself will introduce filth ferments, but, where there are not specific-plague-germs, it is the quantity that tells and the exclusion of the foul feet is an important consideration. To these various poisonous products of saprophytic ferments it often happens that the older swine have by continuous exposure, acquired a comparative immunity, while the young growing pigs perish in large numbers. Feeding pigs in confinement, without green or animal food is very liable to induce costiveness and indigestion which pave the way for the inroad of the hog-cholera germ. A certain allowance of green food, slops, and, above all, a variety of food constituting a well-balanced ration are always desirable. Again, the constitution of the pig is often material. On the continent of Europe it is the high bred English pigs that suffer most, and in all cases a lack of the rugged vigor attained through an active, open air life lays the system more open to a violent attack. Too close breeding must be similarly avoided, together with breeding from the immature, the weak and the debilitated. In this connection it is important to rid the herd of parasitisms which not only weaken the system and lessen the power of resistance, but by the bites or the inflammation induced, open channels for the introduction of the hog-cholera bacillus. _Prevent the Introduction of the Bacillus._ The above precautions are important in obviating infection and favoring a milder type of the disease when the germ has been introduced, but they are but palliatives at best, and will not hinder the development of a plague in the presence of an active and potent virus. Adopted alone they are worse than useless as a means of extinction of the germ: they tend to preserve it. The exclusion of the hog-cholera germ is the one essential thing in prevention and whatever comes short of this must have at best but a partial effect.