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SCIENCE 



[N. S. Vol. XLI. No. 105.5 



and I think there are to-day, even among 

 those who do not follow Apathy and Bethe 

 in their undiseriminating attacks on the 

 neurone theory, many who are seriously 

 asking whether the neurone conception of 

 the reflex exhausts the possibilities or nerv- 

 ous mechanisms. 



For, after all, the distinct service of the 

 neurone theory is its explanation of the 

 mechanism of reflex action. It gives us a 

 satisfactory explanation of simple and 

 even of highly coordinated reflexes; but 

 there are still left problems upon which its 

 staunchest defenders will not claim that it 

 throws much light. The contribution, for 

 example, of the cerebellum to the execu- 

 tion of volitional or reflex actions is not 

 self-evident in tei-ms of the theory; the 

 mechanisms of reenforcement and facilita- 

 tion (Bahnung) are no more easily pic- 

 tured now than before ; and, above all, the 

 whole field of cerebral physiology may be 

 said still to be in the same state as was that 

 of reflex action before Golgi made that for- 

 tunate mistake of putting some pieces of 

 spinal cord which had been hardened in 

 Miiller's fluid into silver nitrate and be- 

 held for the first time a nerve cell in all its 

 glory. 



The diagrammatic clearness of the pic- 

 ture of the reflex mechanism thus revealed 

 has contributed largely to our present men- 

 tal approach to the problems of neTxrology, 

 an approach which is faithfully reflected 

 in our text-book presentations of the sub- 

 ject. The first text-book chapter is largely 

 anatomical, chiefly histological; the next 

 chapter deals with reflex action which is 

 presented to the student as par excellence 

 the typical nervous action; the treatment 

 of the sub,iect then proceeds from the sim- 

 pler reflexes to those requiring a higher de- 

 gree of coordination; accustomed move- 

 ments, such as those of locomotion, receive 

 their explanation as an endless chain of 



reflexes requiring for its operation the 

 structures of the mid- and 'tween brains; 

 finally the attempt to explain everything 

 in terms of reflex action is carried into the 

 field of cerebral physiology. With what 

 success? One has only to read the text- 

 books to find out. Some things, especially 

 localization, are dwelt upon at length; the 

 possibilities of excessively complex coordi- 

 nations are suggested by the anatomical 

 structure; but we miss entirely the satis- 

 faction of seeing the cerebral functions 

 clearly pictured in terms of neurone struc- 

 ture. We trace the "way in" and the 

 "way out"; we see that the connection be- 

 tween the afferent and efferent nerve fibers 

 is in the cortex; but what takes place in 

 the cortex? Is it ob,jectively nothing more 

 than our typical reflex raised to the wth 

 power of complexity? Perhaps it is; but 

 does any one feel reasonably sure of it? 

 For one, I confess I do not. 



However that may be — and I have no 

 intention of discussing the question — this 

 much may certainly be said. We know 

 that there are nervous actions which are 

 not reflexes at all; furthermore, there are 

 nervous actions which usually pass as re- 

 flexes, although they present striking and 

 perhaps fundamental points of difference 

 from the typical reflex arc of our neurone 

 theory. The justification of these state- 

 ments will be attempted in what follows. 

 My present purpose and indeed the purpose 

 of this paper is to challenge the wisdom of 

 making the reflex arc the type of all ner- 

 vous action either in our own thinking or 

 in the presentation of the subject to stu- 

 dents, and to suggest that we would act 

 more wisely to cultivate a more open state 

 of mind with regard to the existence of 

 other possibilities. 



This may be done, it seems to me, by 

 drawing sharply the distinction at the out- 

 set between the following classes of nervous 



