HERRICK'S AN INTRODUCTION TO NEUROLOGY 427 



duction or outline and this limitation is consistently kept in mind. 

 It is so written, however, as to be instructive to the physiologist, 

 clinician and psychologist, or in other words, any student who 

 requires a concise statement of neurological facts. With each 

 chapter goes a bibliography, and these bibliographies taken 

 together comprise the titles of the important contributions to 

 neurology. 



Guided by the idea that the best understanding of the nervous 

 system is to be had by viewing it as a mechanism at work, our 

 author starts with the reflex circuit (a term preferred to reflex 

 arc) as his unit, and proceeds to show how the entire nervous 

 system can be regarded as arranged so as to furnish such reflex 

 circuits, which increase in complexity as, one after another, the 

 more cephalic divisions of the central system (medulla oblongata, 

 thalamus and cortex), are involved in the reactions. This 

 arrangement holds good for the entire vertebrate series, but, 

 as we ascend in the scale, the increasing development of the 

 cephalic divisions brings about responses better and better 

 adapted to favor the welfare of the organisms as a whole. 



The book opens with the statement of general biological 

 ideas, nervous function and the characters of the neuron. Then 

 the discussion of the reflex circuit, anatomical and physiological 

 leads to an account of the general anatomy of the nervous system. 

 This is followed by an examination of the larger divisions and 

 parts. It is of interest here to note that while six chapters are 

 required for even a brief description of the sources and pathways 

 of incoming impulses, a few paragraphs amply serve to indicate 

 the arrangement of the efferent neurons. The remainder of the 

 text is given mainly to describing the arrangement and func- 

 tional connections of those neurons which mediate between any 

 incoming impulses and the neurons of final discharge (efferent 

 neurons). This allotment of space alone serves to indicate the 

 enormous relative development of the afferent and central divi- 

 sions of the nervous system in the higher vertebrates. 



In the course of the presentation our author elects to write 

 the words neuron and axon (sic) without a final e. From Sher- 

 rington he adopts the terms receptor (exteroceptor ; interoceptor 

 and proprioceptor) for the sense organ; and effector for the 

 organ of response. Moreover he has formulated a more precise 

 use of the terms correlation, association and coordination, terms 



