Page:The Scientific Monthly vol. 3.djvu/508

 502 THE SCIENTIFIC MONTHLY

��THE ORIGIN AND EVOLUTION OP LIFE ON THE EARTH*

Bt henry FAIRFIELD OSBORN

COLUMBIA UNITIBBITT^ AHBRXCAN MUflBUM OF NATURAL HISTOBT

LECTX7RB U, PART I

The Evolution of the Vertebrata

Chromatin evolution. Errors and truths in the Lamarekian and Darwinian explanations. Individualitj in character origin, velocitj and cooperation. Origin of the vertebrate type. The laws of convergence, divergence and of adaptive radiation in fishes and amphibians.

SIMON NEWCOMB* considered the concept of the rapid moyement of the solar system toward Lyra as the greatest which has ever entered the human mind. The history of the vertebrates as the visible expression of the evolution of the microscopic chromatin presents a contrasting concept of the potentialities of matter in the infinitely mi- nute state.

The peculiar significance of vertebrate chromatin is its stability in combination with incessant plasticity and adaptability to varying en- vironmental conditions and new forms of bodily action; throughout constant changes of proportion^ gain and loss of characters, genesis of new characters, there is always preserved a large part of the history of antecedent form and function, for chromatin is far more stable than xne surface of the earth. In the vertebrates chromatin evolution is mirrored in the many continuous series of forms which have been dis- covered, also in the perfection of mechanical detail in organisms of titanic size and inconceivable complexity, like the dinosaurs among reptiles and the whales among* mammals which rank with the Sequoia among plants.

There are two historic explanations of the causes of this wonderful process of chromatin evolution, each adumbrated in the Greek period of inquiry. The older, known as the Lamarekian, expressed in modern terms is that the beginning of new form and new function is to be sought in the body cells (soma), on the supposition that cellular actions,

Academy of Sciences, delivered at the meeting of the Academy at Washington, on April 17 and 19, 1916.
 * Fourth course of lectures on the William Ellery Hale Foundation, National

The author desires to express his 8x>ecial acknowledgments to Professor William K. Gregory of Columbia University and the American Museum of Natural History for notes and suggestions in the preparation of this section.

1 Newcomb, Simon, * ' Astronomy for Everybody, ' ' Doubleday, Page & Co. November, 1902, 12mo, pp. 333.

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