Evolution is not another word for Development, and Mr. Spencer has carefully distinguished the one from the other; but the details are too technical for notice in this paper. Evolution may be regarded as "a general term for the history of the steps by which any living being has acquired the morphological and physiological characters which distinguish it." Development is "the process of differentiation by which the primitively similar parts of a living body become more and more unlike one another." Both definitions are Huxley's.

The evolution of organic matter now ,claims attention in detail. Of the origin .of first life, we know absolutely nothing. The doctrine of Evolution does not deal with that. There are, however, many hypotheses upon the subject. Lord Kelvin, the eminent physicist, has suggested that unicellular life may have been transferred to this globe from a wrecked planet. This hypothesis obviously aids us very little, for it merely transfers the original scene of action to some other world. Personally, I prefer the idea that the first protoplasm was produced by the action of the sun upon inorganic matter not unlike the colloids, and that it "fed upon the previous steps in its own evolution." In this connection, I may say that two points are certain, viz., that vegetable life preceded animal life, and that the first forms of life were mere specks of Jelly, without organs. Can these primitive specks be created at the present time? Or, in other words, can protoplasm be manufactured by artificial processes? The answer must be No; not by any process now known, although a great number of experiments have been made with the object of manufacturing unicellular vegetable life. During the years between 1870 and 1880, this question was thoroughly thrashed out, and at first the balance seemed to be very evenly held between the supporters and the opponents of spontaneous generation. The investigations of the late Professor Tyndall, however, conclusively proved that biogenesis, that is, all life from previous life, is the condition at the present day.

But I must add Huxley's words of warning, viz., "that with organic chemistry, molecular physics, and physiology yet in their infancy, and every day making prodigious strides, it would be the height of presumption for any man to say that the conditions under which matter assumes the qualities called vital, may not some day be artificially brought together." And further, "that as a matter not of proof but of probability, if it were given me to look beyond the abyss of geologically recorded time, to the still more remote period when the earth was passing through chemical and physical conditions which it can never see again, I should expect to be a witness of the evolution of living protoplasm from nonliving matter."

The first protoplasm must be extremely ancient, for the remains of seaweeds are found in the oldest strata, and vegetation implies the manufacture of protoplasm from inorganic matter.

When the earth was in the condition to which Huxley referred, the constantly decreasing heat, and the recurrence of the seasons produced, by slow degrees, changes in the congenital character of the forms of life. Every individual varied somewhat from its predecessors, and those forms which possessed variations most suitable to the environment were the ones which eventually survived. The transition from the protophyta, the lowest class of vegetable life, to the protozoa, the lowest class of animal life, must have been a very simple matter in the condition in which the earth then was. Indeed, today the difference between the lowest microscopic animals and the lowest microscopic plants is by no means clearly defined.

Innumerable hosts of life made their appearance upon our planet while the surface was going through the cooling process, and they were, at first, of course, of the most primitive kind. But the same laws were always at work, viz., no two living things were exactly alike when they made their appearance upon this earth, although the differences between several forms might be very slight. Variation was, and is, the order of the day.

The individuals which possessed variations in accordance with the environment persisted, while those having injurious variations had a tendency to disappear. Congenital variations were (and are) transmitted with great certainty. This is Mr. Darwin's "Process of Natural Selection," called by Mr. Spencer "The Survival of the Fittest."