Note 15 — APPENDED NOTES

Biologists are now apparently more disposed than formerly to admit the sudden appearance of considerable and important modifications and rapid developments. Cf. Haeckel, l. c. p. 144, and Bateson, p. 568. He concludes that 'discontinuity of species results from discontinuity of variation.' 'The existence,' he says, 'of sudden and discontinuous variation, the existence, that is to say, of new forms having from their first beginning more or less of the kind of perfection which we associate with normality, is a fact that disposes, once and for all, of the attempt to interpret all perfection and definiteness of form as the work of selection. The study of variation leads us into the presence of whole classes of phenomena that are plainly incapable of such interpretation.' This relative perfection of variations at starting Mr. Bateson attributes in great measure to the principle of 'symmetry,' or 'repetition of parts' in living things. An organism is symmetrical, and thus what happens in one of many similar organs repeats itself normally in all the others. Change in one part is not an isolated fact, but there is 'similarity and simultaneity of change.'