UNIVERJ^. F-CAl! ^ ^-^ 4? &. * ^a ^ / p > ^DNY-SOV^ ^KBAIHa-3? *%Wllff ^l-UBRARY^ A^-BRARY^ ,$k $i ir^^ 1 ir'^ svsn,| IITO'JO^ .OF-CALIF ..; . The Cambridge Manuals of Science and Literature PLANT-ANIMALS CAMBRIDGE UNIVERSITY PRESS SLonDon: FETTER LANE, E.G. C. F. CLAY, MANAGER N>. PRINCES STREET Hantson- H. K. LEWIS, 136, GOWER STREET, W.O. WILLUM WESLEY & SON, 28, ESSEX STREET, STRAND Berlin: A. ASHER AND CO. leipjifl: F. A. BROCKHAUS efo $ork: G. P. PUTNAM'S SONS Bornbau ant) Calcutta: MACMILLAN AND CO.. LTD. All rightt reserved B A. The Green Plant-animal (Convoluta roscoffenns). B. The Yellow-brown Plant-animal ( Convoluta parado.v(i). 40 times natural si/e. PLANT-ANIMALS A STUDY IN SYMBIOSIS FREDERICK KEEBLE, Sc.D PROFESSOR OF BOTANY IN UNIVERSITY COLLEGE, READING ; AUTHOR OF "PRACTICAL PLANT PHYSIOLOGY" Cambridge : at the University Press IQ12 First Edition 1910 Reprinted 1912 With the exception of the coat of arms at the foot, the design on the title page is a reproduction of one used by the earliest known Cambridge printer John Siberch 1521 39 T3 PREFACE X DURING some ten years' work in a small marine laboratory in Brittany it has fallen to me not infrequently to attempt to explain to curious ^visitors what were my objects in going to and fro