The details of technique have been kept as brief as possible; in fact, sufficient only has been said to indicate the main principles involved. In the literature cited, to which the author is indebted particularly for matters relating to technique, will be found full, and sometimes exhaustive, accounts. With regard to the illustrations, these have been selected to illustrate the various methods of reproduction described or to demonstrate the points raised. In those instances where the source has not been acknowledged or the draughtsman or photographer mentioned by name, the figure is by the author: and since the actual making of plates and blocks is of considerable importance, the firms, when known, responsible for their making are mentioned in the Table of Illustrations. In this connexion the author desires to express his appreciation of the skill shewn and care taken by Messrs. Andre, Sleigh and Anglo, Limited, who prepared the majority of the new illustrations which appear in the following pages. The author is indebted to many who have helped in various ways in the production of his work; particularly is he desirous of expressing his warmest thanks to Miss O. Johnston for the charming drawing of _Geranium columbinum_ (Plate 2) and to Mr. Harry Becker for his beautiful lithograph (Plate 1). To Miss S. M. Baker, Dr. W. G. Ridewood, and Miss Winifred Smith thanks are due for the loan of original drawings; also to Mr. Edward Hunter and Mr. Hugh Hunter for information regarding matters of technique and cost. The number of illustrations would have been less but for the generosity of Messrs. Chapman and Hall, the Editors of the "Annals of Botany," "The Imprint," and the "New Phytologist," Professor F. W. Oliver and Mr. G. N. Oliver in lending blocks. Recognition also must be made of the kindness of Mr. Richard G. Hatton in consenting to the use of certain blocks from his admirable "Craftsman's Handbook," of the Delegates of the Clarendon Press for permission to reproduce figure 14, and of Messrs. Frederick Warne and Co. for permission to make use of the wood engraving by Messrs. Edmund Evans, Ltd., of Kate Greenaway's charming Milkmaid. Finally, the author desires to express his sincerest thanks to Mr. Gerard T. Meynell, of The Westminster Press, for the keen interest he has taken in the work, for his help with the illustrations, and for the great care he has taken in the production of the book. University College, London _January, 1915._ INTAGLIO PRINTING In the biological sciences the massing of illustrations into plates is still the favourite method of illustration, although text-figures have recently become more numerous.