204 Literary Notices. 



does the scratch-reflex itself. It is, therefore, only in accord with expectation that 

 the seat of the refractory phase of the scratch-reflex lies where we trace it, in the 

 central nervous organ itself, and somewhere between the motor neurone to the 

 muscle and the receptive neurone from the skin" (p. 65). 



In the principle of the final common ^a/^, Sherrington has found an explana- 

 tion of many of the complex relational aspects of reflexes. Each receptor has its 

 private path; these come together in the so-called internuncial paths, which in turn 

 unite in the fnal common path. Results of the necessity for the use of the same 

 final common path by a number of receptors are: (i) That receptors which have 

 diff"erent or opposite end-effects are forced to use the path successively, not simul- 

 taneously. "The result is this or that reflex but not both together" (p. 117). 

 Thus the final common path prevents the harmful interference of antagonistic re- 

 flexes. (2) That receptors which have similar or harmonious end-effects reinforce 

 one another in the use of their final common path. 'Tf, while the scratch-reflex is 

 being elicited from a skin point at the shoulder, a second point distant, e. g., 10 

 cent, from the other point but also in the receptive field of skin, be stimulated, the 

 stimulation at this second point favors the reaction from the first" (p. 120). 



Between the two classes of receptors, the extero-receptors, which supply the 

 surface of the body and the proprio-receptors, which lie in the depths of the organ- 

 ism, important relations of reinforcement and inhibition are shown to exist. Thus, 

 in the case of the flexion-reflex, "the receptive field includes not only reflex-arcs 

 arising in the surface field, but reflex-arcs arising in the depths of the limb. Com- 

 bined, therefore, with an extero-ceptive area, this reflex has, included in its receptive 

 field, a proprio-ceptive field. The reflex-arcs belonging to its extero-ceptive and 

 proprio-ceptive components cooperate harmoniously together, and mutually rein- 

 force each other's action. In this class of cases the reflex from the muscle-joint 

 apparatus seems to reinforce the reflex initiated from the skin" (p. 131). Accord- 

 ing as a reflex initiated by a given receptor exalts or depresses another simultaneously 

 or successively occurring reflex it may be spoken of as excitatory or inhibitory. 

 In this mutual relation of interference we have, according to Sherrington, an 

 expression of the fundamental importance of the principle of the common path. 

 For every convergence of afferent neurones furnishes a condition for the interference 

 of their reflexes or, in other words, it constitutes a mechanism of coordination. 



The author, far from making hasty or ill-supported general statements concern- 

 ing these matters, builds his structure of facts with skill, system and rare insight 

 to the point at which his conclusions, and in many cases his interpretations as well, 

 are forced upon the reader. I do not wish to give the impression that the book is a 

 highly speculative discussion of the integrative action of the nervous system. It 

 is first of all an account of experimental study of the subject, and secondly an 

 exceedingly valuable discussion of the meaning of the facts which are available. 



In connection with his investigation of the phenomena of irradiation it is note- 

 worthy that Sherrington has discovered a number of important inconsistencies 

 between observed facts and the laws of spinal action as formulated by Pfluger 

 (p. 161). And it is also significant that in calling attention to important evidences 

 of the inadequacy of the so-called laws of reflex action he does not attempt to 

 formulate laws after his own observations but with the wisdom of an investigator 

 who realizes that we are working in the infancy of nervous physiology describes the 

 appearances which he has observed, and, so far as his observations go, states the 



