Let me make my meaning about the dilated heart quite clear. First of all, one must understand that the heart is a pump; that its walls are composed of muscle—though not of the same kind of muscle that the flesh of the arms and legs is made of. Then the valves of this wonderful pump are made of very strong tissue almost as strong as fine canvas. Considering the amount of work that the heart is called upon to do, getting no entire rest either night or day, the wonder is that it can keep on for sixty or seventy years in man, and twenty or more in the horse, in such a very efficient manner. Now, if a man who has been working in an office gets “run down” from overwork, and takes it into his head to go off for a holiday, and part of that holiday is devoted to climbing mountains, he will often come back to his office in a worse condition than when he started. What has happened? He has tried to make his heart muscle do work which it is not prepared to do. He has strained his heart. In other words, this wonderful pump has done its best to cope with the extra work that it was called upon to do, and while it may have succeeded, the effort has affected it, and the result of the extra work performed is that the heart has become _dilated_, and, for the time being, it is not able to do the ordinary work that it is called upon to perform. Provided such a heart is rested and nursed it may come back, but if the possessor of such a heart tries to drive it, and does not rest it, then that heart will fail to do ordinary work, and will most certainly fail if asked to perform extra work. What happens to the untrained office-man happens over and over again on the racecourse to horses that are asked to win races when they are not “ready”—that is, when they are only half-trained; and while they may succeed they often dilate their unprepared hearts in their honest efforts to succeed. The most recent example of this is Salrak, injured by his Newcastle race. Again, when a horse is “ready” and his muscles are fit and he is quite able to run a mile and carry a decent weight, he is asked to run a mile and a half; he makes a mighty effort, and from that day on he never does himself justice in a race, for his effort strained his heart; and not being allowed to rest, his heart remains dilated till the end of his days.