THE WORKS
OF
FRANCIS MAITLAND BALFOUR.
VOL. III.
Memorial Edition.
Cambridge:
PRINTED BY C. J. CLAY, M.A. AND SON,
AT THE UNIVERSITY PRESS.
Memorial Edition.
THE WORKS
OF
FRANCIS MAITLAND BALFOUR,
M.A., LL.D., F.R.S.,
FELLOW OF TRINITY COLLEGE,
AND PROFESSOR OF ANIMAL MORPHOLOGY IN THE UNIVERSITY OF
CAMBRIDGE.
EDITED BY
M. FOSTER, F.R.S.,
PROFESSOR OF PHYSIOLOGY IN THE UNIVERSITY OF CAMBRIDGE;
AND
ADAM SEDGWICK, M.A.,
FELLOW AND LECTURER OF TRINITY COLLEGE, CAMBRIDGE.
VOL. III.
A TREATISE ON COMPARATIVE EMBRYOLOGY.
Vol. II. Vertebrata.
London:
MACMILLAN AND CO.
1885
[The Right of Translation is reserved.]
PREFACE TO VOLUME II.
The present volume completes my treatise on Comparative Embryology.The first eleven chapters deal with the developmental history of theChordata. These are followed by three comparative chapters completingthe section of the work devoted to Systematic Embryology. Theremainder of the treatise, from Chapter XIV. onwards, is devoted toOrganogeny. For the reasons stated in the introduction to this partthe organogeny of the Chordata has been treated with much greaterfulness than that of the other groups of Metazoa.
My own investigations have covered the ground of the present volumemuch more completely than they did that of the first volume; a notinconsiderable proportion of the facts recorded having been directlyverified by me.
The very great labour of completing this volume has been muchlightened by the assistance I have received from my friends andpupils. Had it not been for their co-operation a large number of thedisputed points, which I have been able to investigate during thepreparation of the work, must have been left untouched.
My special thanks are due to Mr Sedgwick, who has not only devoted avery large amount of time and labour to correcting the proofs, but hasmade for me an index of this volume, and has assisted me in many otherways.
Dr Allen Thomson and Professor Kleinenberg of Messina have undertakenthe ungrateful task of looking through my proof-sheets, and have madesuggestions which have proved most valuable. To Professors Parker,Turner, and Bridge, I am also greatly indebted for their suggestionswith reference to special chapters of the work.
CONTENTS OF VOLUME II.
Chapter I. Cephalochorda. Pp. 1-8.
Segmentation and formation of the layers, pp. 1-3.Central nervous system, pp. 3,4.Mesoblast, p.