[October, 1901.] 



THE 



SCIENTIFIC TRANSACTIONS 



ROYAL DUBLIN SOCIETY. 



VOLUME VIL— (SERIES XL) 



XIII. 

 VAEIATION : GEEMINAL AND ENVIRONMENTAL. 



BY 



J. C. EWART, M.D., F.E.S., 

 Eegius Professor of Natural History in the University of Edinburgh. 



DUBLIN: 

 PUBLISHED BY THE EOTAL DUBLIN SOCIETY. 



WILLIAMS AND NOEGATE, 



14, HENRIETTA STKEET, COVENT GARDEN, LONDON ; 



20, SOUTH FREDERICK STREET, EDINBURGH; and 7, BROAD STREET, OXFORD. 



PRINTED AT THE UNIYEESITT PEESS, EY PONSONBY AND WELDEICK. 



1901. 



