i

THE INTERNATIONAL SCIENTIFIC SERIES.
VOLUME XLIX.

ii

iii

iv

v

vi

vii

THE INTERNATIONAL SCIENTIFIC SERIES.

JELLY-FISH, STAR-FISH
AND SEA-URCHINS

BEING
A RESEARCH ON PRIMITIVE NERVOUS SYSTEMS

BY
G. J. ROMANES, M.A., LL.D., F.R.S.
ZOÖLOGICAL SECRETARY OF THE LINNEAN SOCIETY

NEW YORK
D. APPLETON AND COMPANY
72 FIFTH AVENUE
1898

viii

ix

PREFACE.

When I first accepted the invitation of the editorsof the International Scientific Series to supply abook upon Primitive Nervous Systems, I intendedto have supplemented the description of my ownwork on the physiology of the Medusæ andEchinodermata with a tolerably full exposition ofthe results which have been obtained by otherinquirers concerning the morphology and developmentof these animals. But it soon becameapparent that it would be impossible, within thelimits assigned to me, to do justice to the moreimportant investigations upon these matters; andtherefore I eventually decided upon restricting thisessay to an account of my own researches.

With the exception of a few woodcuts in thelast chapter (for the loan of which I am indebtedto the kindness of Messrs. Cassell), all the illustrationsare either original or copies of those in myRoyal Society papers. In the letter-press also Ihave not scrupled to draw upon these papers,xwherever it seemed to me that the passages wouldbe sufficiently intelligible to a general reader.I may observe, however, that although I havethroughout kept in view the requirements of ageneral reader, I have also sought to render thebook of service to the working physiologist, bybringing together in one consecutive account all themore important observations and results whichhave been yielded by this research.

G. J. R.

London, 1884.

xi

CONTENTS.