Page:Popular Science Monthly Volume 12.djvu/188

176 give, but a reference to those facts connected with it that are of chief interest to you. I must bear in mind that this is an institute of clergymen seeking information on a topic which they consider to have a bearing on their pursuits, and that it is from a corresponding point of view that I must present it.

Two explanations have been introduced to account for the origin of the assemblage of organic beings, plant and animal, that surround us. These are conveniently designated as the hypothesis of Creation and that of Evolution.

The hypothesis of asserts that Almighty God called into sudden existence, according to his good pleasure, the different types of life that we see. This hypothesis has an ecclesiastical form, that the world, with all its various animals and plants, was created about six thousand years ago. The work was completed in six days, and was perfect, needing no improvement. At the close of each day the Almighty surveyed what he had done, and pronounced it very good. He brought all the animals thus made before Adam in the garden of Eden to receive their names. There was nothing more necessary, and on the seventh day he rested.

The hypothesis of asserts that from one or a few original organisms all those that we see have been derived, by a process of evolving or development. It will not admit that there has been any intervention of the divine power.

The former of these hypotheses considers each species as independent of all the others; the second considers them as inter-related. Creation reposes on the arbitrary act of God: Evolution on the universal reign of law.

The hypothesis of Evolution in its scientific form presents three factors: 1. Heredity; 2. Environment; 3. Adaptation. By heredity is meant the tendency manifested by an organism to develop in the likeness of its progenitor. By environment, the sum total of the physical conditions by which the developing organism is surrounded the ambient world. By adaptation, the disposition so to modify as to bring an organism and its environment into harmony. This may be accomplished either by progression or retrogression.

As to the origin of organisms, it withholds, for the present, any definite expression. There are, however, many naturalists who incline to believe in spontaneous generation. In its most improved form it occupies itself with two classes of problems, the direct and the inverse, considering in the former the effect of the environment on the organism, and in the latter deducing from the organism the nature of the environment. Thus Schleiden gathers from the structure of the stems of certain pine-trees the distribution of climates at the time of their growth; and the ancient geographical connections of Madagascar and of Australia may be thus ascertained from their fauna.