life-purpose seemed to be to propagate their kind, after which their functional activities began to wane and finally ended in somatic dissolution. The origin of life, notwithstanding much discussion, e.g. at the Dundee meeting of the British Association (1912), is still a mystery, but, according to evidence culled from the geological records and modern biological researches, its first recognizable garb was that of very simple single-celled organisms—simpler even than most of the Protozoa of to-day. Such single cells are universally regarded as the ultimate units in all the complex structural combinations of the organic world. By a critical study of these ever-changing morphological productions, we are enabled to trace the connecting links which bind living things into one united whole, with man as their crowning achievement. As we move along the stream of time the number, variety, and complexity of living forms become bewildering. The quest for food, protection from enemies, and sexual impulses seem to furnish the chief motives of their respective life-activities; and hence the raison d'être for the invention and differentiation of special organs to carry out these purposes. The policy adopted in propagating the species seems to be to flood the environment with their young progeny, with the result that there is a perpetual struggle for existence which always ends in the premature death of the vast majority. For, of the multitudes born, there is room for only a small fraction
