Food, next to inheritance, is the most potent factor in the improvement of the horse. "As a man thinketh, so is he"; as a horse eateth, so is he. This statement may be too sweeping, but, when taken in connection with inheritance, habit and climate, it is true. All the energy which a horse uses is the product of food consumed. Inheritance, climate and special development by use may so modify the structure, both mentally and physically, as to make the body a superior or inferior, an economical or a wasteful living machine through which the energy is expended. One piece of machinery may do a certain amount of work twenty per cent slower than another. This difference may be due to putting the machine at work for which it was not best adapted or to faulty mechanical construction. It may be said, however, that the machine has no mental capacity, while the added efficiency of the horse is frequently due to mental power or brain force. Brain work requires the energy of food to sustain it, - the same, in kind, as is required for work done by other muscular tissues. What really happens is that high mental capacity usually accompanies high muscular efficiency and harmony of the structure called upon to perform the work. The brain of the horse may be likened to the steam-gauge on the boiler; it indicates somewhat accurately the amount of energy ready for use. The results, or work performed, will depend largely on the perfection of the working parts of the engine. High courage usually attends great endurance, but this is not necessarily the case. Other things being equal, real efficiency is more likely to accompany superior and judicious nourishment rather than inferior nourishment. A few days of injudicious feeding of the trotter or racer, just before he makes a great effort, may lose him the prize.

Food plays a most important part, not only in growth and development, but in the efficiency and amount of work as well. Some most marked results are secured by the too liberal as well as the too scanty feeding of many young animals, such as pigs, calves and colts, during the first six months of their lives. Calves designed for the dairy may be greatly injured as to their future performance by being fed too liberally on concentrated food, or dwarfed and injured by being insufficiently nourished. In the same way, young colts, especially after they are weaned, may be handicapped for life by injudicious overfeeding or underfeeding.

Judicious liberal feeding tends to increase size and to produce slight variations in other directions. Food furnishes the material with which to produce variations; inheritance and use largely determine where and how the surplus material shall be used or stored. Liberal but judicious feeding and improved foods have been prime factors in the development of the horse, as well as in that of the great meat-producing animals. The progeny of the fleet trotter may be varied towards a draft-type in a few generations by feeding for increased weight and size and by changing habit from fast to slow, laborious work. Food and use not infrequently overpower inheritance. Uncongenial climate and injudicious feeding may prevent food from accomplishing its legitimate and desired end.