I said that “all the years invent;

Each month is various to present

The world with some development.”—Tennyson.

Although most of my readers will be perfectly acquainted with the theory proposed by Mr. Darwin to account for the various forms of life that we see on the globe, yet, for the sake of clearness, I will briefly enunciate it.

Mr. Darwin first shows that individuals of the same species vary one with another.

He then shows that, owing to the rapid increase of animal and vegetable life, by which many more are born each year than can possibly survive, there is a continual warfare going on among them for food and other necessaries. This he calls the “struggle for life.”

He then shows that if any animal or plant should have, by variation, any organ or property so modified as to give it some advantage over its fellows in the struggle for life, it will, as a general rule, live longer and produce more offspring; and these offspring will have a tendency to inherit the organ or property modified in the same manner: but if in one of these offspring the organ should be still further modified, it win give him a like advantage over his brethren, and his offspring again will have a tendency to reproduce the organ in its more modified state; and so on. This he calls “Natural Selection.”