Transcriber’s notes: In this transcription, italic text is denoted by *asterisks* and bold text by =equal signs=. Subscripts are indicated by _underscores_ (e.g. *a*_1 and *b*_1 in Fig.5 caption) and superscripts by ^ (e.g. *a*^1. in Fig. 9 caption). Page footnotes (renumbered in consecutive order) are now located immediately below the relevant paragraphs. The rare spelling typos noted in the original text have been corrected silently (e.g. invividual-->individual, hyberbola-->hyperbola) but inconsistent use of the ligature æ/ae (e.g. palæontology/palaeontology), inconsistent use of alternative spellings (e.g. learned/learnt), and occasional inconsistencies of hyphenation have been left as in the original. Minor punctuation typos have been corrected silently (e.g. index entries with missing commas). The abbreviation viz. appears in both roman and italic font. Formatting of entries in the Table of Contents does not accurately match that of the corresponding headings in the text, particularly the heading Pt.I-B-3 which contains an extraneous α. In Figure 12 caption, multiple ditto marks have been replaced by the relevant text for greater clarity. THE SCIENCE AND PHILOSOPHY OF THE ORGANISM AGENTS America The Macmillan Company 64 & 66 Fifth Avenue, New York Australasia The Oxford University Press, Melbourne Canada The Macmillan Company of Canada, Ltd. 27 Richmond Street West, Toronto India Macmillan & Company, Ltd. Macmillan Building, Bombay 309 Bow Bazaar Street, Calcutta THE SCIENCE AND PHILOSOPHY OF THE ORGANISM THE GIFFORD LECTURES DELIVERED BEFORE THE UNIVERSITY OF ABERDEEN IN THE YEAR 1907 BY HANS DRIESCH, Ph.D. HEIDELBERG LONDON ADAM AND CHARLES BLACK 1908 *All rights reserved* PREFACE This work is not a text-book of theoretical biology; it is a systematic presentment of those biological topics which bear upon the true philosophy of nature. The book is written in a decidedly subjective manner, and it seems to me that this is just what “Gifford Lectures” ought to be. They ought never to lose, or even try to lose, their decidedly personal character.