NA TURE 



497 



THURSDAY, AUGUST 17, 1916. 



A' 



NEIJROLOGY. 



An Introduction to Neurology. By Prof. C. 

 Judson Herrick. Pp. 355. (Philadelphia and 

 London: W. B. Saunders Co., 1916.) Price 

 7.S-. 6d. net. 



LL the special sciences naturally seek incor- 

 poration into some comprehensive scheme 

 of thought which tends to embody the conceptions 

 that we hold into one organic unity. Neurology, 

 for instance, is brought out, with its component 

 parts of anatomy, physiology, and psychology, 

 into the conception of biology. In no department 

 of human thought is this striving for an organic 

 unity better exemplified than in the co-ordination 

 and subordination of these special studies into 

 the wider and more embracing science of 

 biology. 



The researches which have been brought to- 

 gether in this volume cover an immense reading ; 

 the references amount to many scores of con- 

 tributions, and the book will be of great value to 

 those who seek for an exact knowledge and a 

 succinct account of the ner\'Ous system, the 

 highest controlling machinery' of animal and 

 human life ; for it is the nervous system that deter- 

 mines the adjustments and mutual relationships 

 of all the other systems, as well as those of its 

 own activities, which are so regulated as to pro- 

 mote its own welfare. 



The study of neural actions must proceed from 

 the more simple to the more complex — i.e., from 

 simple reflex action up to acts of consciousness 

 involving deliberation, reflection, and judgment. 

 This progress depends upon (a) a correlation, 

 which is the resultant of all the afferent processes 

 involved ; (b) the co-ordination or orderly co- 

 adjustment and sequence of these — absence of 

 this means inco-ordination ; and (c) the full 

 association of responses secured by individual 

 modifications. In the simple reflex mechanism 

 there are three essential factors : (a) an initiating 

 organ or receptor, sensitive to receive a stimulus 

 which is often far less in intensity than the energy 

 liberated, and which may only be some change of 

 environment acting upon the organ ; (b) a con- 

 ductor to and from a correlating centre ; and (c) 

 an efi"ector or organ of response — the data from 

 these three instruments being as necessary for 

 the most elementary nervous response as they 

 are for the highest mental manifestations, in- 

 cluding abstract thought. The author accepts the 

 classic exp>eriments of H. S. Jennings to explain 

 the adaptation of an organism to its changing 

 environment, and he divides behaviour or conduct 

 (which he calls "action system") into two kinds, 

 viz.. that which is innate and invariable, and that 

 which, through "docility or plasticity," is modi- 

 fiable and variable or labile. He maintains that 

 ever}' reaction contains elements of both, the 

 XO. 2442, VOL. 97] 



variable being characteristic of the higher animal 

 type, implying an intelligently directed choice, yet 

 expressed always through the agency of the lower 

 centres. 



The volume under review commences with a 

 useful biological introduction, describing life as a 

 correlation of physical forces for the conservation 

 of the individual, the continued welfare of any 

 living organism depending upon a properly 

 balanced adjustment between itself and its sur- 

 roundings — i.e., between internal and external 

 relations. An interesting chapter is devoted to 

 the neurone or the nerve cell, which is itself an 

 independent unit, leading an independent life, and 

 separated from its fellows by a reticulated con- 

 tinuum — the synapse — yet it is linked with them 

 by this fibrillar structure, which acts as a damper 

 or a resistance to the passage of impulses, thus 

 limiting excitability. The neurone effects the 

 conduction of physico-chemical waves towards the 

 effectors, but in one direction only, and this by 

 means of its dendrites, axon, and collaterals, 

 which are continuous with the ner\-e fibre. The 

 author omits to mention the important discovery 

 that the living neurone consists of protoplasmic 

 granules, each surrounded with a lipoid oxidising 

 substance ; the Xissl granules of the neurone, 

 or the tigroid bodies, being artefacts after 

 death. 



The last four chapters are devoted, fully 

 but concisely, respectively to the physiological 

 psychology of pain and pleasure — i.e., the 

 hedonic tone of consciousness connected with 

 modifications of the subject by the object; 

 the track of the pain nerves in the spinal 

 cord being illustrated in the text; to the general 

 anatomy of the cerebral cortex, and here, we 

 note, there is no reference to the extremely valu- 

 able and important work 'of Dr. G. A. Watson on 

 the mammalian cortex ; and to reflex acts, instinct 

 and intelligence. This chapter opens up two or 

 more interesting psychological points, viz., 

 whether reflex acts and instinct are only biological 

 adaptations, and whether instincts are intelligent 

 acts. In regard to these the opinions of psycho- 

 logists differ, but the view of the majority is that 

 every instinctive act is determined by intelligence. 

 Between the chapters named the text is mainly 

 histological and descriptive. 



The book is concise and scientifically accurate, 

 but owing to its extreme technicality it is difficult 

 to read except by the expert anatomist or the 

 senior advanced student. It certainly should be 

 in the hands of every teacher of psychiatry. The 

 illustrations are numerous and well chosen to illus- 

 trate the text, the bibliography is extensive, and 

 the index as perfect as can be made and doubly 

 useful through the help of the glossary. It may 

 safelv be added that the author has succeeded in 

 his aim "to disentangle the inconceivably complex 

 interrelations of the nerve fibres which serve all 

 the manifold functions of adjustment of internal 

 and external relations." 



Robert Armstroxg-Joxes, 



C C 



