450 Journal of Applied Microscopy. 



nineteen plates containing about two hundred fifty figures. Four appendices 

 deal respectively with the collection of samples ; tables, formulae, and reagents 

 useful in the microscopic study of water ; the bibliography of the subject ; and a 

 glossary' of the technical terms used in Part II. The bibliography is very exten- 

 sive and complete, containing nearly five hundred titles, which refer not only to 

 papers in English, but also in German and French, and which are well arranged 

 according to topics. There are a few important omissions, however. Surely, 

 the list should include the published parts of the first volume of Engler and 

 Prantl's " Die natiirlichen Pfianzen-familien," containing as they do the Conju- 

 gate and Chlorophycese, with Schiitt's treatise on the diatoms. And if volume one 

 of the " Traite de Zoologie concrete " (La cellule et les Protozaires) by Delage 

 and He'rouard be included in the list of references for " Protozoa," why should 

 not volume five (Les vermidiens) of the same work be given in the list for 

 " Rotifera " ? The latter list is very meager, and the student will find this lav- 

 ishly illustrated volume of the " Zoologie concrete " of much value. Again, the 

 reference to Weltner's " Spongillidenstudien " (Archiv fiir Naturgeschichte, 1893, 

 pp. 209-244) relates only to the literature of the Spongillidae, while through 

 some oversight, apparently, no reference is made to Weltner's own important 

 researches w^hich are given in the next part of the same " Archiv," pp. 245- 

 284. 



The subjects treated in the first part of the book are the history of the various 

 earlier methods of examination ; the object and methods of microscopical exam- 

 ination ; microscopic organisms in water from different sources ; limnology, 

 geographical, seasonal, horizontal, and vertical distribution of microscopic 

 organisms ; odors of water-supplies ; storage of surface water ; storage of ground 

 water ; growth of organisms in water pipes. This portion of the book, as may 

 be seen from the list of topics just given, will be of great value to water-works 

 engineers, and sanitarians, containing as it does a brief and non-technical discus- 

 sion of the trustworthy results obtained by the biologists and engineers of this 

 country and of Europe. Much of the author's own original work is here given. 



In the second part the system of classification of the larger groups followed 

 is not such as is accepted by systematists in general, but rather one which the 

 author regards as being more useful from the practical standpoint. The genera 

 described are those more commonly found in the waters of lakes and rivers. 

 Sanitarians will probably regret that the author has not stated in the description 

 of each genus what is now known concerning its influence upon potable water. 

 Owing to the method employed in reproducing the plates, many of the figures 

 suffer from lack of clearness and detail. Asterionclla (PI. II, fig. 4) is represented 

 as having the basal ends of the individual frustules united into a complete circle. 

 This arrangement is, of course, impossible, since, owing to the diatom's mode of 

 fission, the circle is always broken. A number of unimportant typographical 

 errors occur, but these will undoubtedly be corrected in the future editions which 

 the intrinsic value of the book will necessitate. 



Charles Wright Dodge. 

 University of Rochester. 



