3^4 



NATURE 



[August 17, 1905 



confusion. The chapter on senile dementia is dis- 

 tinctly good and very instructive. 



Under " psychoses without a well-determined 

 etiolog)', which are apparently based upon a morbid 

 predisposition," are found manic-depressive insanity, 

 paranoia, and constitutional psychopathic conditions, 

 such as mental instability, sexual perversions and in- 

 versions and obsessions. Paranoia is very briefly de- 

 scribed under the title of "Reasoning Insanity." 

 We strongly disagree with the author in his use of 

 this term; it is by no means a good one, and is, in 

 addition, confusing, since other writers have used it 

 as designating the maniacal stage of manic-depressive 

 insanity. 



Epilepsy and hysteria are described under the head- 

 ing of " Psychoses Based on Neuroses," and the con- 

 cluding chapter is devoted to the consideration of 

 the arrest of mental development. 



The book is well translated, and the index is care- 

 fully compiled. This manual undoubtedly has its 

 merits, but, as we have already stated, it will scarcely 

 appeal to the practitioner, as the description of treat- 

 ment is somewhat meagre, and the student will find 

 the subject-matter almost too condensed. In any 

 future edition the author will do well to correct these 

 defects, for by so doing he will render his book a 

 useful manual on psychiatry. 



OVR BOOK SHELF. 

 Experiments with Plants. By Dr. W. J. V. Oster- 



hout. Pp. x + 492; illustrated. (New York: The 



Macmillan Company; London: Macmillan and Co., 



Ltd., 1905.) Price 5*'. net. 

 The author defines his aims in the following words 

 (p. 7) : — " The numerous questions which young 

 people ask about plants are best answered by them- 

 selves. . . . To put them in the way of doing this 

 so far as possible is the object of this book." In 

 accordance with this plan, the apparatus used is of 

 a rough and home-made description, constructed of 

 fruit jars, lamp chimneys, clothes' pegs, india-rubber 

 bands, and sealing-wax. Much ingenuity is shown 

 in the design of apparatus so put together. Whether 

 a sufficient degree of stability is always obtainable 

 may perhaps be questioned, but from the author'^ 

 point of view the advantages of his method certainly 

 outweigh any such shortcomings. One great merit 

 in the book is the insistence on the necessity of control 

 experiments, which are especially needful with rough 

 methods. The book is divided into chapters headed 

 " The Work of Roots " — of leaves, of stems, &c. — 

 ending up with a chapter on " Making New Kinds 

 of Plants," which is a statement of what breeders 

 and experimenters on variability have done rather than 

 instructions for the making of such experiments. 



The author very properly recommends common 

 plants for use; but why students of botany should 

 be confined to such names as " Kentucky Coffee 

 Tree," "Dusty Miller," "Live Forever," "Switch 

 Plant," it is difficult to say. Occasionally we find the 

 scientific name, and in this way we learn that a 

 " Wandering Jew " is a Tradescantia. 



Most of the experiments are clearly described, but 

 we have been puzzled over some of them. For 

 instance (p. 191), the method of answering the 

 question, " Does the leaf decompose carbon dioxide? " 

 seems to us to involve passing a lighted candle under 



NO. 1868, VOL. 72] 



water into a jar of air. Here and elsewhere in the 

 book the author neglects simple and striking methods. 

 It is important that the student should be convinced 

 that oxygen is given off by green leaves in light. The 

 above-mentioned experiment is not satisfactory, 

 whereas Engelmann's blood method is both simple 

 and convincing. Again, the well-known plan of count- 

 ing the bubbles given off by submerged plants in 

 light, though not free from errors, gives useful com- 

 parative data for the study of assimilation. In the 

 same way we think that more fundamental experi- 

 ments should have been given under the heading of 

 " Stomata." Stahl's cobalt method, which is merely 

 mentioned in a note, can be used bv the most elemen- 

 tary of students to demonstrate important facts. 



In spite of some faults, the book will be found of 

 value to anyone compelled to give a course of 

 physiological botany under conditions which preclude 

 the use of ordinary laboratory fittings. 



Conversations on Chemistry. Part i. General 

 Chemistry. By W. Ostwald. .\uthorised trans- 

 lation by Elizabeth Catherine Ramsay. Pp. v + 250. 

 (New York : John Wiley and .Sons; London : Chap- 

 man and Hall, Ltd., 1905.) Price 6.?. 6d. net. 

 The German original of this book has already received 

 sympathetic notice in Nature, and in connection with 

 the translation now before us it is necessary to add 

 little more than that Miss Ramsay has done her 

 work with much skill, and has made the dialogue 

 not less natural and vivacious than it is in the original. 

 It is impossible to read the book without a feeling of 

 refreshment and amusement, or without admiration 

 of the ingenuity and resource of its philosophical 

 author. It seems hardly fair to say that we have 

 here a revival of Dr. Brewer or Mrs. Marcet. There 

 are two striking differences between the old and the 

 new dialogues. In the first place neither master nor 

 pupil in Prof. Ostwald 's book is endowed with that 

 austere and depressing piety of mind which, to the 

 unregenerate, provided perhaps the most afflicting 

 feature of the older works. In the second place Prof. 

 Ostwald 's book shows a masterly treatment not only 

 of the real difficulties of chemistry in itself, but a 

 perfect appreciation of the pitfalls that beset the pupil 

 in the early stages of learning. It is difficult to sup- 

 pose that any teacher will fail to find something useful 

 or to gain some valuable hints from reading the book, 

 and on this ground it must be warmly recommended. 



It would, however, be a misfortune if a teacher 

 constrained his teaching to the exact course of the 

 dialogue, and, of course, it would be worse still if 

 he set so many pages as a lesson to be learned by the 

 Dupil. The real usefulness of the book will probably 

 lie in the example it affords of the life that may be 

 imparted to teaching when, on the one hand, the 

 pupil is allowed a fair chance of thinking out things 

 for himself and a full opportunity of frankly saying 

 what he thinks, and when, on the other hand, the 

 teacher takes the part of a guide, philosopher, and 

 friend who has a soul above dictionaries and examin- 

 ation papers. .\. S. 



Mathematical Recreations and Essays. By ^^^ \\'. 



Rouse Ball. Fourth edition. Pp. xvi + 402. 



(London : Macmillan and Co., Ltd., 1905.) Price 



ys. net. 

 This edition differs from the third by containing 

 chapters on the history of the mathematical tripos at 

 Cambridge, Mersenne's numbers, and cryptography 

 and ciphers, besides descriptions of some mathematical 

 recreations previously omitted. The book has thus 

 become more miscellaneous in character, but the 

 additions fit in very well, and are all entertaining. 

 Mr. Ball writes with enjoyment of his subject, and 



