HEREDITY AND EVOLUTION IN PLANTS - 1920 - FRONTISPIECE Restoration of a scene along a sluggish creek in Texas and New Mexico during the late Carboniferous Upper Pennsylvanian and early Permian times. The lowlands of this period doubtless swarmed with reptiles such as shown in the picture, and with other animals, now extinct. Some specimens of the giant dragon-flies had a spread of wings of two feet. The fern-like trees and the bushy plants in the foreground are Cycadofilicales. To the right of the water are wide stretches of the huge scouring rush Calamites on the left bank of the stream are the unbranched Sigillarias still as prominent as earlier in the coal period, and on higher ground to the left the branched Lepidodendro. One must view this scene as one of many such landscapes, with evervarying detail, along streams and inlets. Cordaites, which in later Devonian time made the first great forests of which there is record, is still present, though not shown. So, too, there are hidden in the recesses of the forest the forerunners of the modern coniferous types, as well as other forms destined to give rise to the angiosperms. Landscape from Williston, adapted from Neumayr. To the Memory of BENJAMIN STUART GAGER What a science Natural History will be whcn . . . a l the laws of change are thought one of the most important parts of Natural History.-Charlrs Darwin. Lellcrto J. D. Hooker. - PREFACE - The present little book was originally intended to be merely a reprint of Chapters XXXI to XXXVIII of the authors Fundamentals of Botany. The reprinting of those chapters was suggested by comments received from various correspondents, who pointed out that the subject matter which they cover hadnot been elsewhere presented in, so concise a treatment in one volume, and in a manner suited, not only to beginning students, but also. to more general readers. The chapter on Experimental Evolution has received the approval of the author of the mutation theory, as being an accurate presentation of the essentials of that theory. I have especially appreci- ated, writes Professor de Vries, the statement of the difference between fluctuating and saltative variation, which is, to my mind, the real empirical basis for the theory, far more than the experiments on mutation with single plants. The relation of my view to Darwinism is misunderstood by many authors, and it is a great satisfaction to me that you have outlined it in such a plain way. In the preparation of the copy for reprinting, considerable new matter has been added, certain sentences and paragraphs, pertinent only to an elementary text-book, have been omitted, and others recast, and several fresh illustrations have been introduced, either as new or as substitutes. Chapters X, Geographical Distribution, and XIII, The Great Groups of Plants, and the Bibliography are new. No attempt has been mhde to cite the voluminous periodical literature in the Bibliography, but needless to state, this has been freely consulted and drawn upon. Numerous citations are given as foot-notes, especially in Chapter X. In going over the chapters it also became evident that since, in order to read them understandingly, one must have a clear conception of the facts of the lift history of a vascular plant, it would be best to introduce from the Fundamentals of Botany the three chapters viz. XIIXIV on the life history of the fern. As stated in the Prefa, ceto that, book, while the ultimate problem of botany is the development of the kingdom of plants, the more immediate and fundamental problem is the development of the individual plant...