Heinemann's Scientific Handbooks
THE BIOLOGICAL PROBLEM OF TO-DAY
HERTWIG
Heinemann's Scientific Handbooks
THE BIOLOGICAL PROBLEM OF TO-DAY
PREFORMATION OR EPIGENESIS? THE BASIS OF A THEORY OF ORGANIC DEVELOPMENT
BY
PROFESSOR DR. OSCAR HERTWIG
DIRECTOR OF THE SECOND ANATOMICAL INSTITUTE OFTHE UNIVERSITY OF BERLIN
Authorized Translation
BY
P. CHALMERS MITCHELL, M.A.
WITH AN INTRODUCTION BY THE TRANSLATOR AND A GLOSSARY OF THE TECHNICAL TERMS
LONDON
WILLIAM HEINEMANN
1896
[All rights reserved]
PREFACE
Shortly after the appearance of Dr. Oscar Hertwig's treatise 'Präformationoder Epigenese?' I published in Natural Science (1894) a detailedabstract of it. But the momentous issues involved in the problem ofheredity, and the great interest excited by Dr. Weismann's theories, makeit desirable that a full translation should appear. By the kindness of Dr.Hertwig and his German publisher, this is now possible. I have prefixed anintroduction, written for those who are interested in the general problem,but who have little acquaintance with the technical matters on which theargument turns. In the actual translation I have tried no more than to givea faithful rendering of the German. After no little perplexity, I haverendered the German word Anlage as 'rudiment.' It is true, a doublemeaning has been grafted upon the English word, and it is widely employedto mean an undeveloped structure, without discrimination between incipientand vestigial character. I use it in the etymological sense, as anincipient structure. For the difficult words, Erbgleich andErbungleich, a succession of new terms have been suggested. Here I usefor the first term the word 'doubling,' for the second 'differentiating.'
P. C. M.
TRANSLATOR'S INTRODUCTION
Inquiry into the problems of heredity is beset with many difficulties, ofwhich not the least is the temptation to argue about the possible, or theprobable, rather than to keep in the lines of observation. Setting out froma laborious and beautiful series of investigations into the anatomy of theHydromedusæ, Weismann came to think that the organic material from whichthe sexual cells of these animals arose was not the common protoplasm oftheir tissues, but a peculiar plasm, distinct in its nature andpossibilities. In the course of several years, Weismann not only continuedhis own investigations in the many directions that his conceptionsuggested, but made abundant use of that new knowledge of the nature andproperties of cells which has been the feature of the microscopy of thelast decade. His theory of the germplasm gradually grew, undergoing manyalterations, so that even in its present form he regards it as tentative.Neglecting the numerous modifications and accessory hypotheses by which hehas sought to adapt the theory to the phantasmagorial complexity of organicnature, the main outline of the theory is[Pg viii] as follows: A living being takesits individual origin only where there is separated from the stock of theparent a little piece of the peculiar reproductive plasm, the so-calledgermplasm. In sexless reproduction one parent is enough; in sexualreproduction equal masses of germplasm from each parent