Mr. V. A. Clark, as a student in horticulture in the University of Vermont, first undertook a critical examination of NÄgeli'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 NÄgeli'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 NÄgeli'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.