Produced by Bryan Ness and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) A MECHANICO-PHYSIOLOGICAL THEORY OF ORGANIC EVOLUTION BY CARL VON NAeGELI SECOND EDITION CHICAGO THE OPEN COURT PUBLISHING CO. 1914 COPYRIGHT, 1898 BY THE OPEN COURT PUBLISHING CO. CHICAGO PREFATORY NOTE. Mr. V. A. Clark, as a student in horticulture in the University of Vermont, first undertook a critical examination of Naegeli's _Mechanico-Physiological Theory of Evolution_ as a part of his regular junior work. After a half year's study and the preparation of a short thesis, Mr. Clark had become so far intimate with Naegeli's work as to make it seem best for him to continue the study through his senior year. This study involved extended translations from the text, including Naegeli's _Summary_, which, considering its difficult accessibility to American students, has been chosen for publication. The work has been done chiefly by Mr. Clark, but has all been under my immediate supervision, and I have given the whole matter a final restudy and revision. Those who have had any experience with similar work will know how impossible it is that all mistakes should have been avoided, and it would be a kindness to the translators if readers would point out any defects, in order that they may be corrected. F. A. WAUGH. University of Vermont, July 1, 1898. A MECHANICO-PHYSIOLOGICAL THEORY OF ORGANIC EVOLUTION. SUMMARY. In this summary I shall in general pursue a course the reverse of that which my main work follows.[A] I shall proceed from the primitive, unorganized condition of matter and endeavor to show how organized micellar substance has arisen in it, and how, from this micellar substance, organisms with their manifold properties have arisen. Since such a synthesis of organisms out of known forms of matter and force is still far removed from a conclusion strictly in accord with physical law, the process becomes comprehensible and obvious only by exact knowledge of the discussion that has preceded. Although the synthetic method reveals more clearly the weaknesses of the theory than do analytic investigations, yet I considered it helpful to make this presentation in order to give a clearer idea of the mechanico-physiological theory, and at the same time to test its worth.