266 



NA TURE 



[January 23, 1896 



thus originated, and which is, in fact, the cause of 

 the origin of species, independently of, and apart from 

 other causes, discussed in the following pages, such as 

 impediments to fertilisation (Kyesamechanism), and 

 sudden development (Halmatogenesis)." 



It is probable that various causes, acting unequally in 

 different groups of animals and plants, have contributed 

 to the origin and differentiation of species ; and there is 

 certainly much to be said in favour of the view that 

 evolution proceeds along definite lines, and also that 

 it is liable to be arrested at certain definite points. With 

 respect to the latter phenomenon, we may refer to Dr. 

 Leuthner's monograph of the Odontolobidce, a family of 

 East Indian stagbeetles, published in the Transactions 

 of the Zoological Society for 1886, which illustrates this 

 very clearly. It may also be observed in the common 

 earwig. 



Besides the discussion of the various points noted in 

 the above-quoted paragraph, this work contains inci- 

 dental remarks on the influence of heat and cold on 

 butterflies reared artificially ; and on mimicry, &c., as 

 well as a reply to some criticisms by the late Dr. Haase 

 on the first volume of the work. 



While the philosophical part of the book will be read 

 with interest by students of evolution, the special part, 

 with its excellent illustrations of closely allied species and 

 varieties, will be useful to collectors of foreign butterflies 

 generally. 



RECENT WORKS ON PHYSIOLOGY. 

 A Manual of Physiology. By G. N. Stewart, M.A., 



D.Sc, M.D.Edin. (London: Ballifere, Tindall, and 



Cox, 1895.) 

 Physiology. By A. Macalister, LL.D., M.D., F.R.S. 



" Manuals of Science Series." (London : Society for 



Promoting Christian Knowledge, 1895.) 

 Elementary Physiology. By J. R. Ainsworth Davis, B.A. 



(London : Blackie and Son, 1895.) 



WE have at the present time several very excellent 

 text-books of physiology in English, adapted for 

 the various needs of different classes of students. And 

 to prevent these being inconveniently increased, it is a 

 matter of tacit agreement amongst teachers of physiology 

 that it is undesirable to afford a welcome to any new 

 text-book, unless it has itself the highest claims to 

 recognition. These claims may be based either upon 

 some novel method of treatment of the subject, or upon 

 the impression on the work of an author's high personal 

 authority. 



Adopting such a standard of criticism as the above, 

 we first proceed to consider Dr. Stewart's manual. The 

 fact of the author possessing so brilliant a reputation in 

 the application of physics to physiology, is sufficient to 

 make a work at his hands of the utmost value in certain 

 iDranches of the subject. There are other influences to 

 which Dr. Stewart has been exposed, which also tend to 

 ■enhance the value of his work. The teaching methods 

 of the Edinburgh school involve both conciseness and 

 •dogmatism, and these are as desirable in elementary 

 instruction as they are pernicious in more advanced. 



The manual which Dr. Stewart has written is to be 

 regarded as an elementary text-book^ for it is really some- 

 NO. 1369, VOL. 53] 



thing more than a mere manual. The methods through- 

 out involve a concise expression of varying views, and 

 the author's personal preference for any particular view 

 is clearly indicated. Such a method we consider very 

 desirable in a book of this character. As regards the 

 facts incorporated, they include in general the very latest 

 work that the time of publication permitted, and indicate 

 an acquaintance with the progress of physiology as is 

 possible only with a specialist in that branch of science. 

 Interwoven with the academic exposition are detailed 

 instructions for practical work. We have not very much 

 faith in the success of this innovation. It is extremely 

 inconvenient for a student to have to carry from his 

 home to his laboratory a somewhat bulky volume, and 

 the instructions are of no value except in the laboratory. 

 We certainly think that it would have been much better 

 to have omitted from such a book as this all practical 

 instruction. We would like to offer some criticism also 

 upon this practical instruction. It is to a considerable 

 extent of such a character as to be impossible even to an 

 American student, though Dr. Stewart dwells on the 

 greater opportunities existing on the other side of the 

 Atlantic for practical investigation. We have some 

 doubts, also, concerning the advisability of introducing the 

 so-called electro-physiology to the extent that has been 

 done. It is not that too many pages have been allotted 

 to it ; on the contrary, if introduced at all, it requires 

 many more than the author saw his way to give. The 

 result is that, though so much has been referred to, it 

 has been treated so briefly that the fault of brevity, 

 vagueness, is only too apparent. W^e think that few 

 students will derive the proper amount of information 

 from this section unless it be largely supplemented by 

 the personal instruction of a teacher. 



For certain classes of students, however, the book will 

 be of special service, and we thmk that it will undoubtedly 

 be regarded as a valuable addition to our present text- 

 books of physiology. 



For Prof Macalister's little manual we have nothing 

 but praise. So much of elementary physiology as it 

 is generally understood is identical with elementary 

 anatomy that the physiologist is not at more advantage 

 than the anatomist in describing the more elementary 

 facts. A somewhat novel arrangement of the different 

 points treated upon has been adopted. The author has 

 commenced by describing the nature of food and diges- 

 tion. This is already a matter of some slight acquain- 

 tance to one who has not studied physiology, and he is 

 thus led on through partially familiar paths. 



Sections then follow, treating of the blood, the circula- 

 tory system, respiration, the skeleton, joints, the nervous 

 system, and the organs of the senses. A small amount of 

 histology has also been introduced. The author through- 

 out the book teaches valuable hygienic lessons from the 

 explained phenomena. In a later edition a few correc- 

 tions might be introduced ; and when that is done, the 

 book will be an excellent guide to the explanation of 

 elementary physiological principles. 



Mr. J. R. Ainsworth Davis's work is intended by the 

 author (i) for elementary students in general; (2) for 

 students of general biology who wish to supplement the 

 subject on the physiological side ; (3) students of 

 psychology ; (4) students of agriculture and dairying. 



