. The study of animal life. Zoology. 202 The Study of Animal Life part m. One must be careful not to press the idea of recapitulation too far, (i) because the individual hfe-history tends to skip stages which occurred in the an- cestral progress ; (2) because the young animal may acquire new characters which are peculiar to its own near lineage and have little or no importance in connec- tion with the general evolution of its race; (3) because, in short, the resemblance between the indi- vidual and racial history (so far as we know them) is general, not precise. Thus we regard Nauplius and Zoe

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Image ID: PG3RAB
. The study of animal life. Zoology. 202 The Study of Animal Life part m. One must be careful not to press the idea of recapitulation too far, (i) because the individual hfe-history tends to skip stages which occurred in the an- cestral progress ; (2) because the young animal may acquire new characters which are peculiar to its own near lineage and have little or no importance in connec- tion with the general evolution of its race; (3) because, in short, the resemblance between the indi- vidual and racial history (so far as we know them) is general, not precise. Thus we regard Nauplius and Zoea rather as adaptive larval forms than as representatives of ancestral crustaceans. More- over, if one insists too much on the approximate parallelism be- tween the life-history of the indi- vidual and the progress of the race, one is apt to overlook the ^â ^â¢^ j^saSQs-^ h sometimes circuitous path, be- cause its far-off ancestors did so. To some extent we may think of inherited constitution as if it were the hand of the past upon the organism, compelling it to become thus or thus, but we must realise that this is a living not a dead hand ; in other words these meta- morphoses have their efficient causes in the actual con- ditions of growth and development. The suggestion of Kleinenberg referred to in a preceding chapter helps us, for. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Thomson, J. Arthur (John Arthur), 1861-1933. New York, C. Scribner's sons [printed at the Edinburgh press]