“The adorning thee with so much art Is but a dangerous skill; Like to the poisoning of a dart, Too apt, before, to kill.” Most of the Carnivora may be looked upon as man’s natural enemies, for he has no chance of making headway unless he can keep “the beast of the field” from “increasing upon him.” Amongst primæval men, the tribes who made the best weapons to keep off these, the destroyers of their families, were certain to succeed best in the struggle for existence, so that the act of sharpening a flint-stone to repel the attack of some wild beast may be said to have prepared the way for civilisation, for flint knives led to bronze hatchets, bronze hatchets to axes and hammers of iron, and when once iron-working was understood and appreciated, civilisation went on with gigantic strides. Besides acting as one of the severest of schoolmasters in the hard school of adversity in which man has been trained, the flesh-eaters serve to keep in check, and indirectly to bring to perfection, the grass-eating tribes. Upon these--the Oxen, Antelopes, Wild Asses, &c.--the large Carnivora delight to prey; in so doing they have to put forth all their powers, their agility, strength, and cunning, while the Herbivores, at the same time, have acquired caution and swiftness of foot in the highest degree, in order to escape from their ruthless and implacable destroyers. While the larger beasts of prey keep in check the troops of great hoofed animals, the smaller kinds, such as Cats and Ferrets, have a most important office in thinning the constantly multiplying ranks of gnawing animals, such as Rats and Mice, which would otherwise prove a plague of the worst description. Indirectly, too, our Carnivora may even influence largely the spread of certain kinds of vegetation: for instance, as Mr. Darwin has shown, where there are no Cats there is no clover! This seems strange, not to say fabulous, but it is known that clover will only flourish when there are plenty of Humble-bees, the only insects able to carry the fertilising pollen from flower to flower, and so ensure a good supply of seed for the next crop. Now, Field Mice are particularly hostile to Humble-bees, knowing quite well where to find their nests and combs, and how to get at their honey, of which they are very fond. Thus, where Field Mice exist in great numbers, Humble-bees will be comparatively few. But Mice are chiefly kept down by Cats, and so the end of this biological “house that Jack built” is that to ensure a good crop of clover it is advisable to have plenty of Cats about!