NA TURE 



73 



THL'RSDAV, NOMIMBER 28, 1907. 



THE VERTEBRATE NERVOUS SYSTEM. 

 The Nervous System of Vertebrates. By Prof. J. B. 

 Johnston. Pp. 370. (London : J. Murray, 1907.) 

 Price 155. net. 



THE author's aim has been " to produce a text-book 

 of comparative neurology, giving an account of 

 tlic nervous system as a whole, to trace its phylo- 

 genetic history, and to show the factors which have 

 determined the course of evolution." He states (in 

 the preface) that the functional point of view is the 

 chief characteristic of the present work, but that 

 (p. 10), as an introduction to the study of the nervous 

 system, it deals chiefly with structure. 



The work starts with a brief, though clear, sum- 

 marv of the various methods used in the investigation 

 of the nervous system, and then proceeds to a very 

 useful description of the general morphology of the 

 same, more particularly as found in the Cyclostoma, 

 Selachians, and .Amphibia. Then follows a lucid 

 account of the main features and processes in the de- 

 velopment of the nervous system, especially as seen 

 in the lower vertebrates, and valuable light is thrown 

 on the evolution of those parts of the nervous system 

 associated more directly with the visceral arches, 

 spiracular and branchial clefts, and of the lateral line 

 structures. We note the author, without hesitation, 

 ascribes taste, or gustatory, functions to structures 

 distributed more or less widely on the outside of the 

 head, and in e.xtreme cases, as in some bony fishes, on 

 the fins and over almost the entire body, yet the true 

 and specific function of these organs remains still to 

 be determined. 



In a brief description of the nerve elements and their 

 functions the formulation of the neurone theory is 

 ascribed (p. 10) to \\'aldeycr, in i8gi, whereas this dis- 

 tinguished savant did little more than suggest the 

 term " neurone " for structures the conceptions of 

 which in this connection had been gathering strength 

 since the days of Schleiden and Schwann, some fiftv 

 3ears earlier. 



In discussing nerve degeneration and regeneration 

 the author inter alia states (p. go) that the pro.ximal 

 portion of a divided peripheral nerve remains in a 

 healthy condition. This may be true for some of the 

 lower vertebrates, but is incorrect for many of the 

 higher forms, as v. Gehuchten and others have 

 proved. 



In chapters v. to xii. the author discusses with much 

 originality and lucidity the four kinds of nervous ; 

 activity, viz., the somatic afferent, somatic efferent, 

 visceral afferent, and visceral efferent, and these chap- 

 ters, together with that on the evolution of the 

 cerebral hemispheres, may be accounted some of the 

 most valuable in the book. The description of the 

 neuromasts is especially useful, and though on debate- 

 able and obscure ground the whole matter is sugges- 

 tively and clearly treated. However, the author not 

 infrequently falls into the common error of confusing 

 or using indiscriminately the term " afferent " and 

 "sensory," and throughout the work seems more at 



NO. 1987. VOL. yy] 



home with the subject as it concerns the lower than 

 with that of the higher vertebrates, especially in con- 

 nection with recent work. 



Perhaps, too, reference may be made to the follow- 

 ing assertions : — On p. no it is stated that " sensory 

 cutaneous fibres emit collaterals which cross directly 

 to the opposite side of the spinal cord." These cross- 

 ing fibres have never yet been shown degenerated 

 in a mammal, and the statement is incorrect for at 

 least the majority of the higher vertebrates. Again, 

 on p. 1 15 it is stated that " a part of the secondary- 

 neurones of the V. nerve ascend on the same side of 

 the bodv," whereas recent work tends to show the 

 contrary, at least in mammals. 



In the description of the cerebellum several state- 

 ments call for modification. Thus it is stated, p. 240, 

 that " all three peduncles of the cerebellum carry both 

 incoming and outgoing fibres," whereas many recent 

 workers on higher vertebrates have shown the inferior 

 cerebellar peduncle to contain only afferent fibres. 

 .Again, on p. 243, it is stated that " primary somatic 

 sensory fibres from spinal roots enter the cerebellum 

 directly." On p. 245 that " the direct cerebellar tract 

 from Clarke's column ends, according to most ob- 

 servers, in the deep grey nuclei of the cerebellum " 

 (instead of in the cortex of the vermis) ; and on the 

 same page that " the axones of the Purkinje cells pass 

 to the spinal cord and inferior olive," and that " the 

 fibres passing to the Nucleus Dentatus seem to include 

 fibres from the posterior column nuclei." With all of 

 these statements we are in disagreement, and natur- 

 ally, therefore, with deductions drawn therefrom. 

 Moreover, we regret in the account of the cerebellum 

 the absence of reference to the views of Hughlings 

 Jackson, or to the recent work by Sherrington, whilst 

 the general conception that the cerebellar cortex is 

 a large recipient surface for afferent impulses 

 from all parts of the body; that this gives off its 

 efferent impulses along the fibres to the cerebellar 

 nuclei, and these gain efferent impulses to the bodily 

 structures as advocated more particularly by Clarke 

 and Horsley, Dejerine, Thomas, Klimoff, &c., seems 

 insufhcienlly emphasised. 



The last chapter offers briefly a review of the more 

 important facts concerning the neopallium, and 

 would have been more useful had it in the discussion 

 of the sensori-motor areas treated of such sub-divisions 

 as the audito-sensory, audito-psychic, visuo-sensory, 

 and visuo-pyschic, which are not mentioned; and had 

 the motor area not been depicted as involving the 

 post-central gyrus which Griinbaum and Sherrington 

 disproved for Anthropoids, and many surgeons have 

 disproved in man. 



On the whole, the book gives the impression of 

 having been written by an able zoologist interested 

 in neurology, rather than by a pure neurologist, and 

 therein lies a good deal of its value. No more abstruse 

 problem has ever been presented to man than that 

 of the vertebrate nervous system, and in the present 

 work the author presents a very readable and succinct 

 account of his subject, which forms a valuable and 

 welcome addition to the literature relating to it. 



W. P.^GE M.w. 

 E 



