PROCEEDINGS 



OF THE 



American Philosophical Society 



HELD AT PHILADELPHIA 



FOR PROMOTING USEFUL KNOWLEDGE 

 Vol. LVI. 1917. No. 6. 



CONTENTS 



Mechanism of Overgrowth in Plants. By ERwax F. Smith .... 437 



Recurrent Tetrahedral Deformations and Intercontinental Torsions. 

 By B. K. Emerson 445 



Early Man in America. By Edwix Swift Balch 473 



PHILADELPHIA 



THE AMERICAN PHILOSOPHICAL SOCIETY 



104 South Fifth Street 



' I917 



