Show when a man Is thirty tears of ae all men who employ animals in kaw how their speed falls off with increasing age race horses are withdrawn from the track shortly after they have arrived at the foil possession of their force they are still good for competitions in bottom and are capable for many years yet of doing excellent trotting service but they cannot ran in trials of speed mans capacity to run likewise decreases after he has passed thirty years and the professional couriers who are still seen in tunis running over large distances in an incredibly short time are obliged to retire while still young those who continue to run after they i are forty years old all finally succumb with grave heart affections popular science monthly |