Routledge Revivals
Experimental Analysis of Development
This book, first published in English in 1932, serves as an introduction to experimental embryology. This title, while covering in-depth the field of investigation, presents the general issues surrounding this particular study rather than just providing an analysis of particular results. This title will be of interest to students of introductory biology and the history of science.
Experimental Analysis of Development
Bernhard Drken
Translated by
H. G. & A. M. Newth
First published in 1932
by George Allen & Unwin Ltd
This edition first published in 2016 by Routledge
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1932 George Allen & Unwin Ltd
All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers.
Publishers Note
The publisher has gone to great lengths to ensure the quality of this reprint but points out that some imperfections in the original copies may be apparent.
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The publisher has made every effort to trace copyright holders and welcomes correspondence from those they have been unable to contact.
A Library of Congress record exists under LC control number: 32032529
ISBN 13: 978-1-138-95831-9 (hbk)
ISBN 13: 978-1-315-66123-0 (ebk)
EXPERIMENTAL ANALYSIS OF DEVELOPMENT
by
BERNHARD DRKEN
Translated by
H. G. & A. M. NEWTH
First published in German under the title of
Grundriss der Entwicklungsmechanik
FIRST PUBLISHED IN ENGLISH IN 1932
All rights reserved
PRINTED IN GREAT BRITAIN BY
UNWIN BROTHERS LTD., WOKING
The experimental analysis of development has become an indispensable part of Biology. Very many of those whose attitude towards the fundamental problems of Biology is important are still quite unaware, however, of the problems and conclusions of this branch of study. This applies particularly to medical men. Certain results of outstanding importance have indeed become known, but there is far from being any general comprehension of the real significance of analytical embryology. Often, indeed, we find that the words experimental embryology and analysis of development convey nothing of the ideas for which they stand. Yet there is perhaps no other branch of Biology which leads the student so directly to fundamental questions concerning the living organism.
This lack of knowledge is partly accounted for by the fact that there is no short book which, while covering the whole field of investigation, presents concisely its great problems rather than its particular results. Considerations of time alone would prevent the readers with whom we are concerned from lightly undertaking the more comprehensive works on the subject.
It seems, too, that there is need of a book of moderate size for those students of Biology who are fortunate enough to be able to study the subject more fully afterwards in the laboratory and the lecture-room; and the need is naturally greater in the case of students who have no such opportunity.
The present book was written to meet these requirements, and it should not be read as a substitute for the more comprehensive works which it cannot replace. It is intended to serve as an introduction only; but as such it may perhaps help to awaken a growing interest in experimental embryology.
In view of the purely didactic purpose of the book, it was considered best to omit from the text all references to literature and original papers. If these are required they will be found in full in my Lehrbuch der Experimentalzoologie, and in the other works mentioned at the end of the present book.
B. DRKEN
BRESLAU,
July 30, 1929
In preparing an edition of this book for English readers we have not attempted elegance of style. The reader will find-particularly in the more philosophical passagesplain traces of the original German idiom; but he is begged to note that our chief concern throughout has been to convey what we believed to be the thought of the author, without any gloss of interpretation. We have therefore been most literal in those places where the difficulty of the text has offered the greatest temptation to be free.
The mode of employment of certain expressions calls for explanation. The zygote in its early stages of development, before the differentiation of organs, has been throughout called a germ, as distinct from an embryoi.e. an Amphibian blastula, gastrula, or neurula would be so called. The convenient abbreviations,
-blastomere,
-blastomere,
-blastomere have been employed, as is now fairly usual, to indicate a single blastomere of the two-, four-, or eight-cell stages respectively, the denominator of the fraction giving the total number of cells in the germ. The word regenerate has been freely used as a substantive to signify that which arises as the result of regenerative processes. If this be a coinage it is justified by its utility and by the precedent of degenerate.
In accordance with the wish of the author, the word modification is always used for the similar German word, as meaning a non-heritable change produced by the environment, though English usage does not draw so clear a line between this and variation. From the real difficulty presented by Mehrleistung we were able to escape only by using a theological equivalentsupererogationwhich, it is feared, may be less familiar to the younger generation of readers than it is to us.1
In discussing the relation which the rudiment of an organ may bear to the developed organ itself, Professor Drken makes use of two distinct antitheses: that between direkt and indirekt, and that between unmittelbar and mittelbar. These words he has used in a sense quite special to the context. On consideration we have elected to translate unmittelbar and mittelbar in the usual way as direct and indirect; but for direkt and indirekt the words immediate and mediate have been used. Since the passages in which these words occur form an important part of the authors thesis, we may perhaps add that direct in this usage implies obligatory, while indirect implies facultative. The words mediate and immediate, on the other hand, imply respectively the mere presence or absence of intermediate steps or processes.
Finally, we wish to thank Professor Drken for valuable criticism and advice during the course of the translation, and to acknowledge the patience of our publishers in face of many delays.
H. G. N.
A. M. N.
Note
Supererogation [f. L. supererogare, pay out beyond what is expected], doing of more than duty requires.
