It must be remembered that the above quantities are only approximate. Ten pounds of carbo-hydrates would in all probability not be consumed by a racehorse - perhaps not more than two-thirds of that amount; yet a large waggon-horse, subjected to severe labour, would consume fully that quantity. And, as has been already hinted, the animal body is not a mere machine which only requires an increase in fuel to develop an increase of power for work; for there is a limit to absorption and assimilation of the pabulum, this being smallest for fats, next for albuminates, and largest for carbo-hydrates. If the work imposed upon a horse is larger than his system can sustain, even where the food allowed is unlimited in quantity, this will not permit him to undergo the toil without injury. A horse will succumb to overwork, however well he may be fed.