Page:The Scientific Monthly vol. 3.djvu/512

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��THE SCIENTIFIC MONTHLY

��momeDtnm,* while the other m&y be retarded into a state of absolute inertia or equilibrium. These are the extremes of character-velocity which result in the states known as development, balance and degen- eration. In many parts of the skeleton de- velopment and degeneration bo obviously follow use and disuse that Cope was led to propose a law of Bathmism (growth force) and to explain the energy phenomena of use [ and disuse in the body tissues as the catue , of the appearance of corresponding energy potentialities in the chromatin. In other words, that the energy of development or of degeneration in the bodily parts of the ia- f corresponding parts in the germ. As pointed 1 this supposed law consists in its not being in-

��PlO. 8. FlUT DP

or JfmboolkeHvn lemmbra. ■

Via. 4. FIBST DPPES MOLl

Dv Euproiogonta tmercemit.

��dividual is inherited b out above, the defect i: variably applicable.

�� ��' GlOUraiC AFTXiUKCI AKD EPOCHS OV UlXtM

RADIATION (Expansion) and Diuinution ( Comiactioh ) or tbk Civb Ciashes or VICBTEBBATiil> ANIMALS. Prepared by Osbom and Gregorj.

3 In physics mDmentum equals mass X velocit}'. In biology momentum and inertia refer to tbe relative rate of character change both in individual develop- ment (ontogeny) and in evolution (phylogeny). Character-paraHax would ex- press the differing velocities of two charBCtors. Thus the character-paraUaz of the right and left horns in the Brontotheriins (titanotheree) is very gmall, i. e,, they evolve at nearlj- or quite the sanie rate; on the other hand, the character- parallax between the premolar teeth in these animals is very great The ehar-

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