SCIENTIFIC LITERATURE. 



709 



sons's HOMO to Know the Ferns.* The 

 name of the author is new, but the au- 

 thor herself is a familiar friend to all 

 lovers of American field and wild-wood 

 life, for she is none other than Mrs. Wil- 

 liam 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, in- 

 troduces us to them, and before she is 

 done makes us well acquainted with 

 them. " It seems strange," she says, 

 " that the abundance of ferns every- 

 where has not aroused more curiosity as 

 to their names, haunts, and habits." 

 Possibly it is because they are so com- 

 mon that we are not at pains to seek 

 greater intimacy with them. Then, they 

 depend on the beauty of graceful pro- 

 portion, which is less obvious to careless 

 eyes than that of color. First, Mrs. Par- 

 sons 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, de- 

 velopment, and fructification, gives a list 

 of notable fern families and descriptions 

 of the American ferns classified into 

 eight groups according to the arrange- 

 ment of their spores, and completes the 

 work with indexes of Latin and of Eng- 

 lish names and of technical terms. 



Tlie Microscopy of Drinking Water f 

 is intended by Mr. WMpple primarily to 

 serve as a guide to the water analyst and 

 the water-works engineer by describing 

 the methods of microscopic examina- 

 tion, assisting in the identification of 

 the common microscopic organisms 

 found in drinking water, and interpret- 

 ing the results in the light of environ- 

 mental 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 



* How to Know the Perns. A Guide to the 

 Names, Haunts, and Habits of our Common 

 Ferns. By Prances Theodora Parsons. New 

 York: Charles Scribner'e Sons. Pp. 215. Price, 

 $1.50. 



t The Microscopy of Drinking Water. By 

 George Chandler Whipple. New York : John 

 Wiley & Sons. Pp. 300, with nineteen plates. 



illustrated, but the last ten years' accu- 

 mulations of data are not otherwise at- 

 tacked. The illustrations have been 

 largely drawn from Massachusetts cases, 

 from which there may be differences else- 

 where, but not very great as to micro- 

 scopic organisms. The latter half of the 

 book is devoted to descriptions of a lim- 

 ited number of organisms, chosen f9r 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. 



It is evidence of appreciation of Dr. 

 Wetterstrand' s Hypnotism and its Ap- 

 plication to Medicine * that, written in 

 Swedish, it has been translated into Ger- 

 man and Russian, and now into English. 

 The German work, from which the pres- 

 ent translation is made, was enlarged 

 from the original, and embodied the re- 

 sults of additional experience. The au- 

 thor disavows the intention of writing a 

 manual or text-book, and modestly as- 

 sumes only to have given " unpreten- 

 tious notes by a physician who, under 

 the pressure of a fatiguing and engross- 

 ing practice, has not been able to de- 

 velop his rich material into a more com- 

 plete form." The book is characterized 

 by the translator as more practical than 

 theoretical, and as offering the results 

 of conscientious and able observation. 

 Hypnosis is defined by Dr. Wetterstrand 

 as embracing a number of various condi- 

 tions of the nervous system, which can 

 be produced in different ways. " We 

 recognize phases of the greatest variety, 

 from a slight heaviness in the limbs, the 

 most superficial somnolence enabling the 

 hypnotized subject to hear and perceive 

 the least noise, to the deepest sleep, from 

 which the greatest distiirbance can not 

 awake him, and wherein every sensation 

 disappears and permits the most serious 

 surgical operation without pain." The 

 author believes that the majority of peo- 

 ple can be brought into any of these 



* Hypnotism and its Application to Medicine. 

 By Otto Georg Wetterstrand, M. D. Authorized 

 translation (from the German edition), by Henrik 

 G. Petersen, M. D. Together with Medical Letters 

 on Hypno-Suggestion, etc. By Henrik G. Peter- 

 sen, M. D. New York : G. P. Putnam's Sons. Pp. 

 166. 



