Nothing, as breeders are aware, is so fatal to the well-being of a herd, or leads so quickly to degeneration, as the perpetuation of the race by immature males. That procreation should be the act of the robust adult alone, is evidently an axiom with nature herself in successful production; it is doubtless of the highest importance to keep up the normal standard of strength and size. As a fact, the presence of the immature male among a herd of cattle is only permitted whilst he is still quite impubescent. Then banishment by the master of the herd is inevitable at a later stage. These exiles, although thus apart from the main herd, remain in touch with it, so to speak, and we find in consequence, in continual proximity of the troop of the patriarch and his females, a small band of males, which, as is evident from their colour and general physical resemblance, are its direct product. The relations between this mob and the old male are always strained, the latter has constantly to be on the watch to _shield his marital rights_. For long the mere menace of his presence suffices for such protection, but with age--the young bulls becoming more bold--struggles take place which sooner or later, from mere force of numbers, end in the rout or death of the parent. We may here cite the mention made by Mr. Darwin[2] of Lord Tankerville’s account of the battles of the wild bulls in Chillingham Park: ‘In 1861 several contended for mastery, and it was observed that two of the younger bulls attacked in concert the old leader of the herd, overthrew and disabled him, so that he was believed by the keepers to be lying mortally wounded in a neighbouring wood. But a few days afterwards one of the young bulls approached the wood alone, and then the monarch of the chase, who had been lashing himself up for vengeance, came out and in a short time killed his antagonist. He then quietly joined the herd, and long held undisputed sway.’ I may add from my own observation among half-wild herds in the colonies, that often when the old patriarch is not absolutely killed in such cases, he is forced to quit the herd. He then becomes a solitary exile, always exceptionally savage and dangerous to approach or molest. It seems to me probable that we have here an explanation of the occurrence of the existence of the well-known ‘rogue’ elephant, which is always a male and notoriously dangerous.