As to elimination by enemies, it is well known to naturalists that throughout nature battle within battle is continually recurring with varying success. When weaker animals are preyed upon by stronger ones, and self-defense is useless, the bulky and slow animals are eliminated, while the swift and agile ones escape; the stupid are destroyed, while the cunning often survive. As to elimination by competition, the stronger animals kill the weaker ones, and then quarrel and fight with one another over the prey, the strongest, etc., getting the food. While weaker animals are being preyed upon by various enemies, and are thus eliminated, these enemies are also competing with one another for the prey. At the same time that the stupid and slow creatures are being destroyed by their captors, thus leaving the more cunning and agile animals in possession of their habitat, the stupider and less active captors are gradually eliminated by competition, through failing to capture their more agile and cunning prey. The agency of Natural Selection in bringing about the innumerable adaptations of animals and plants, and, therefore, causing transmutations of living creatures, can most interestingly and instructively be illustrated by a study of the _coloration of animals and plants_. As a correct idea of the mode of operation of Natural Selection, and the pronounced results attained thereby, is very desirable, it will well repay the reader to study _in extenso_ the relations of _color-patterns_ to _environment_. The whole subject is nothing but repeated illustrations of one principle, viz.: Natural Selection. This fact and the interest of the subject will justify the numerous details.