170 



NA TURE 



[December 21, 1905 



The three books the titles of which head this review- 

 are typical of the three classes of men who have made 

 the electrical industry. Mr. Whetham's of the seekers 

 after truth who are always asking for more light and 

 have discovered all the fundamental principles on 

 which the industry is based, Messrs. Ashe and Keiley's 

 of the pioneers who have developed the practical possi- 

 bilities of these principles, and " Modern Electric 

 Practice " of the great majority who are content to 

 follow where others lead but whose united efforts have 

 placed at the disposal of all mankind the forces latent 

 in the philosopher's jar. Maurice Solomon. 



HYGIENE AT SCHOOL. 



Text-book of Hygiene based on Physiology for the 



use of School Teachers. By A. Watt Smyth. Pp. 



xvi + 256. (London: Simpkin, Marshall and Co., 



Ltd.) Price 6s. 



MRS. WATT SMYTH rightly says in her pre- 

 face that 



" Physiology is the science of the action of the body 

 in health, hygiene the practical application of this 

 science; it is obviously impossible to understand the 

 laws of hygiene without a knowledge of the funda- 

 mental principles of physiology." 



She has set herself the task of providing a text- 

 book of hygiene founded upon physiology, for the 

 use of teachers, in order that they may comprehend 

 the hygienic needs of the pupils committed to their 

 charge. Hitherto the books written with this object 

 (and there are several) have either been good as text- 

 books of elementary physiology and bad as text- 

 books of elementary hygiene, or vice versa ; and Mrs. 

 Watt Smyth is to be congratulated upon having 

 brought these two subjects, which are so intimately 

 associated with each other, into a fairly satisfactory 

 relationship, and upon having dealt with each in a 

 very commendable manner. It must be said, how-' 

 ever, that the physiological matter of the book is the 

 better, and that in many instances the hygienic matter 

 could have been presented in greater fulness of detail 

 with advantage. The space given to physiology far 

 exceeds that devoted to hygiene, and while the de- 

 mands of the former subject upon space are neces- 

 sarily somewhat greater, there can be no two opinions 

 thai the physiology in many respects is too elaborate 

 for the purpose to which this book is dedicated. Some 

 non-essential matter is included; for instance, a de- 

 scription is given of the ethmoid bone, the number 

 of bones it articulates with, and the time when ossifi- 

 cation is complete ; the number of separate centres of 

 ossification is also given of other cranial bones ; the 

 minute structure of the salivary glands is entered into 

 with unnecessary fulness, for the teacher is informed 

 that 



" the secreting cells of the salivary glands are 

 of two main types, according as the secretion of the 

 gland is mainly serous or albuminous (Parotid), 

 mainly mucous (sub-lingual) or both (sub-maxillary). 

 In a gland that has not been recently secreting, the 

 mucous secreting cells, which are round or oval, are 

 distended with a clear substance, mucigen, from 

 which mucus is formed when the gland becomes I 



no. 1S86, vol. 73] 



active. The cells of the glands which yield an albu- 

 minous secretion are cubical and almost fill up the 

 acini. Their protoplasm is full of dark granules be- 

 fore secretion occurs; when it begins, the granules 

 diminish in number and finally almost completely 

 disappear." 



These instances are referred to as illustrations of a 

 certain lack of appreciation, which is evident here 

 and there, of what is essential and what is not ; for it 

 is impossible to see what practical application can be 

 claimed of the knowledge of the above facts. The 

 illustrations and diagrams, moreover, are anatomical 

 and histological. There is no single illustration of 

 any form of sanitary apparatus or appliance, and these 

 matters are referred to in the text often in such a 

 cursory manner that the reader would find it impos- 

 sible to form a satisfactory conception of their true 

 nature. 



Mrs. Watt Smyth deals with each subject on an 

 excellent plan. First she gives a brief account of the 

 physiology of the subject discussed (with special 

 reference to any notable feature of these physiological 

 processes in childhood), and then she proceeds to deal 

 with the hygienic principles and practices which rest 

 upon these foundations. Her scheme is well illustrated 

 in the chapter on respiration and air; the nose, 

 larynx, trachea, and lungs are first described, then 

 the mechanism of respiration is explained, next the 

 constitution of the air prior and subsequent to respira- 

 tion is set out, and then there follows the consider- 

 ation of the problems of ventilation and heating, and 

 the evil consequences which result when these pro- 

 visions are insufficient or faulty. 



The other chapters of the book fairly cover the 

 necessary ground, and the chapters upon the special 

 senses and the muscular system (the latter including 

 a syllabus of physical exercises based on the Swedish 

 system) are very complete. 



In conclusion, reference should be made to the 

 great care which has been exercised in the preparation 

 of this work. The facts set out are entirely accurate 

 and the opinions expressed are sound, without excep- 

 tion. The author acknowledges her indebtedness for 

 information and counsel from such authorities as Dr. 

 Dawson Williams, Dr. James Kerr, and Miss Turner. 



REGENERATION IN ROOTS. 

 Studien iiber die Regeneration. By Prof. B. Nemec. 

 Pp. 3X7; with 180 figures in the text. (Berlin: 

 Gebr. Borntraeger, 1905.) Price 9.50 marks. 

 T N this somewhat bulky volume the author describes 

 and discusses at some length the result of his 

 numerous experiments on the regenerative processes 

 that occur in wounded roots. 



It is well known that if the tip be removed from a 

 growing root a new apex is commonly differentiated, 

 growth in length commencing once more when the 

 new tip has become completely formed. The objects 

 of Dr. Nemec 's investigation have been to endeavour 

 to throw some light on the nature of the process of 

 regeneration itself, the causes that initiate and deter- 

 mine its occurrence, and the meaning of the physio- 

 logical events that are associated with it. The 



