Most naturalists believe that immeasurable ages ago life on our earth existed only in the primary form of a sort of seed or germ. This beginning of life on our planet was what biologists call
protoplasm: basic life-substance, containing potentialities of growth and development, but at first so little organized as to contain only a hint of what we mean now when we speak of living creatures in their present variety.
Over long ages, under countries influences and agencies which can only partly understand, the life-stuff developed and grew in complexity, becoming organized in variously shaped structures of pattern. Multiplying increasing, unfolding, it “opened up” as a plant-seed sprout, thrusts up its stem, puts forth branches and leaves, until it achieves a form that in the seed was only hidden promise.
Naturalists sometimes speak of the “tree of life”. This is one way of saying that it is all one united growth. Under all the differences of life forms there is unity, a vital relation among them, for they go back together to a common source and an hour when the seed of life began growing, long ago.
All animal life in our world is a single great organization: animation. This whole living entity – now vast, multiformed, comprising thousands of interrelated species functioning with an intricacy of parts united into a whole, but once only protoplasm – in a sense had a birth. It grew through seasons of increase, adaptation, trial-experience, the drawing out of capacities and potential. When human eyes and mind first looked upon animation,
man found it richly differentiated, complex, a teeming integration of inter-working parts. Once it was only foreshadowing protoplasm, only a seed of all this.
