A very handsome book, in what to many are the most graceful and interesting forms of vegetable life, is Mrs. _Parsons's How to Know the Ferns_.[I] The name of the author is new, but the author herself is a familiar friend to all lovers of American field and wild-wood life, for she is none other than Mrs. William Starr Dana, who had already given us How to Know the Wild Flowers and According to Season. In this book she does as she did with regard to the wild flowers--takes her readers to the haunts of the ferns and into their company, introduces us to them, and before she is done makes us well acquainted with them. "It seems strange," she says, "that the abundance of ferns everywhere has not aroused more curiosity as to their names, haunts, and habits." Possibly it is because they are so common that we are not at pains to seek greater intimacy with them. Then, they depend on the beauty of graceful proportion, which is less obvious to careless eyes than that of color. First, Mrs. Parsons discourses of Ferns as a Hobby, and the pleasure we may derive from them; then she tells when and where to find them, defines the terms used in speaking of them, explains their fertilization, development, and fructification, gives a list of notable fern families and descriptions of the American ferns classified into eight groups according to the arrangement of their spores, and completes the work with indexes of Latin and of English names and of technical terms. [Footnote I: How to Know the Ferns. A Guide to the Names, Haunts, and Habits of our Common Ferns. By Prances Theodora Parsons. New York: Charles Scribner's Sons. Pp. 215. Price, $1.50.] _The Microscopy of Drinking Water_[J] is intended by Mr. _Whipple_ primarily to serve as a guide to the water analyst and the water-works engineer by describing the methods of microscopic examination, assisting in the identification of the common microscopic organisms found in drinking water, and interpreting the results in the light of environmental studies. A second purpose is to stimulate a greater interest in the study of microscopic aquatic life and general limnology (the lessons of lakes and ponds) from the practical and economic point of view. The work is elementary in character. Principles are stated and illustrated, but the last ten years' accumulations of data are not otherwise attacked. The illustrations have been largely drawn from Massachusetts cases, from which there may be differences elsewhere, but not very great as to microscopic organisms. The latter half of the book is devoted to descriptions of a limited number of organisms, chosen for the most part from those commonest to the water supplies of New England, and those that have best illustrated the more important groups of microscopic animals and plants. Most of the illustrations have been drawn from living specimens or photomicrographs of such, but some are reproduced from other sources.