. Animal life and intelligence. Biology; Animal intelligence; Psychology, Comparative; Evolution. Heredity and the Origin of Variations. 141 developed, and the ovum from which the daughter is developed, are simply two fragments separated at different times from the same continuous germ-plasm.* Both develop under similar circumstances, and their products cannot, therefore, fail to be similar. How variation is possible under these conditions we shall have to consider presently. Now, although I value highly Professor "Weismann's. Fig. 21.—Egg and hen. I. "The egg produces the ;
. Animal life and intelligence. Biology; Animal intelligence; Psychology, Comparative; Evolution. Heredity and the Origin of Variations. 141 developed, and the ovum from which the daughter is developed, are simply two fragments separated at different times from the same continuous germ-plasm.* Both develop under similar circumstances, and their products cannot, therefore, fail to be similar. How variation is possible under these conditions we shall have to consider presently. Now, although I value highly Professor "Weismann's. Fig. 21.—Egg and hen. I. "The egg produces the ; II. "The hen produces the ; In/, the dints pro- duced by the environment are not inherited \ in II. they are. The letters indicate successive individuals. The small round circles indicate the eggs. luminous researches, and read with interest his ingenious speculations, I cannot but regard his doctrine of the con- tinuity of germ-plasm as a distinctly retrograde step. His germ-plasm is an unknowable, invisible, hypothetical entity. Material though it be, it is of no more practical value than a mysterious and mythical germinal principle. By a little skilful manipulation, it may be made to account for any- * It will, of course, be understood that a minute fragment of germ-plasm is capable of almost unlimited growth by assimilation of nutritive material, its properties remaining unchanged during such 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 Morgan, C. Lloyd (Conwy Lloyd), 1852-1936. Boston, Ginn
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