Nov. II, 1875J 



NATURE 



23 



force of gravityiis one of those which aids the circulation ; 

 that " all those vessels which carry blood to a capillary 

 system are called arteries ; " that in " scaly amphibia "— 

 by which we assume reptiles are meant — the two ventricles 

 always communicate, which is not true as far as the cro- 

 codiles and alligators are concerned ; and that the heart of 

 a warm-blooded animal, removed from the body, will 

 continue to beat " so long as a supply of oxygenated blood 

 is provided." 



The term " secretion " in its widest sense is said to 

 denote " all those processes in which substances quit the 

 blood in an altered or unaltered condition." This involves 

 the inclusion of that simple nutritive diffusion into tissues 

 which results in the origin and growth of bone, cartilage, 

 &c. ; an unnecessary complication, we cannot help think- 

 ing, and one apt to mislead. When it is stated that 

 '• nothing is known about the formation and regeneration 

 of bone-tissue, except the morphological appearances 

 presented in the various stages," justice is not done to Dr. 

 Beale's most ingenious and highly probable explanation of 

 the process by which it comes into existence. 



The second portion of the work discusses the energetic 

 relations of the body. Parts give indications of having 

 been evolved from the author's inner consciousness, when 

 he might have appealed to sound fact. On the whole we 

 prefer the way in which the subject is treated in Dr. 

 Pavy's excellent work on " Food," Prof. Hermann's 

 theory of muscular contractility, based entirely on 

 slender analogies, does not impress itself on our atten- 

 tion more than does the not less satisfactory one of Dr, 

 Radcliffe. 



The " liberating " or " discharging " apparatus, in other 

 words the nervous system, occupies the third section of 

 the work. As our knowledge of the ner\'es is very super- 

 ficial, remarks the author, it 'must suffice to establish 

 empirically the conditions .which increase, diminish, or 

 destroy irritability. This is done in a most exhaustive 

 and excellent manner. Prof. Hermann regards the 

 phenomenon of electrotonus as an effect of contact, the 

 contents of nerve-tubes which are dying or in activity 

 being negative to the contents of nerve-tubes which are 

 living and at rest. The chapters on special sense v/ill 

 be read with particular interest, from the masterly manner 

 in which they are written. Why so much space is 

 devoted to the horopter, a surface the physical relations 

 of which are as much connected with stereoscopic photo- 

 graph cameras and double magic lanterns as with eyes, 

 we do not know. With regard to the author's ideas on 

 the recent views promulgated by Hitzig, Fritsch, Noth- 

 nagel, and Ferrier, we will quote his own words. "The 

 movements which have recently been induced by elec- 

 trical stimulation, since they do not occur after mechanical 

 or chemical stimulation, may very well be set down to 

 the irritation of more deeply seated regions, for the latter 

 are unavoidably exposed to the diffusion of currents. 

 .... No results as to the nature and distribution of the 

 functions of the cortex, even of the value of approxima- 

 tions, can be deduced from these experiments." 



In the fourth section of the work a short account is 

 given of the development of the embryo, not detailed 

 enough to be of much service, except to the initiated. 

 This rapid glance at the contents of Prof. Hermann's 



work indicates that it adopts a method of treatment that 

 is more modem than most. In perusing it in detail the 

 incorporation of the results arrived at in all directions by 

 physiologists during the last twenty years, makes its 

 value still further apparent. The many conflicting state- 

 ments which have sometimes to be made, without any 

 explanation being given, leave several questions without 

 any definite answer. Such must for some time be the case 

 in a science so young as physiology. The^authorities for 

 the different statements introduced are given in every case 

 where there might be any doubt, and the book would 

 have been still further serviceable if references had been 

 introduced to the publications in which the results are 

 described, as well as to the author's name. Many, in 

 looking through the work, will feel that much of the 

 method and many of the phenomena there explained, 

 which, although they have not made their way into our 

 text-books, have been current in the oral tradition of 

 physiological circles \ they must remember that a con- 

 siderable amount of capital has been made out of foreign 

 investigations by those who have done little more than 

 dole them out in a different language from that in which 

 they originally appeared.! 



The arduous task of translation has been most con- 

 scientiously performed by Dr. Gamgee, who has evidently 

 weighed, carefully and acutely, the unavoidably difficult 

 forms of expression employed, many necessarily quite 

 new on account of the novelty of the conceptions deve- 

 loped. Taking for example the word " Schwellenwerth," 

 as employed with reference to Fechner's psycho-physical 

 law which is shortly explained ; at the suggestion of Dr. 

 Sanderson it has been translated " liminal intensity," an 

 expression which does not at first sight explain itself, as 

 does " initial intensity," the rendering which first occurred 

 to Dr. Gamgee. In physics " initial " is employed of 

 velocities, and we are not sure that any other term was 

 necessary. 



In conclusion, there is no doubt that the appearance of 

 this work has greatly reduced the need, at the present 

 time, for any other treatise on the;. Elements of Physiology. 



WHITE CONQUEST 



White Conquest. By William Hepworth Dixon. Two 

 vols. (London : Chatto and Windus, 1876.) 



MR. DIXON has been again in America, this time 

 to collect evidences of the struggle between the 

 races that is being waged on that wide battle-field. 

 Although his method of treating the subject is not such 

 as quite to bring his work within the critical sphere 

 of Nature, and although the author makes no attempt 

 to treat his subject scientifically, still even the scien- 

 tific reader, the student of ethnology or of the charac- 

 teristics ^cf the various races of men, and he who takes an 

 interest in the struggle for existence wherever it is being 

 carried on, will find much in Mr. Dixon's striking pic- 

 tures well fitted both to interest and instruct. It is not 

 in our province to criticise the quality of the artistic 

 element in the work, but about its fascination there can 

 be no doubt. Of course the work is one-sided. We do 

 not use the term by way of depreciation, but in its literal 

 sense. Mr. Dixon's aim is to represent, by means of a 



