MEMORY AND ASSOCIATION OF IDEAS. 11 



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curious fact to hold in the case of muscular tissues of various 

 animals, from the Medusae upwards.* 



Again, I concur with M. Ribot in his opinion that the 

 physical basis of memory consists partly in a more or less 

 permanent molecular change or " impress " produced upon 

 the nervous element affected by the stimulus which is re- 

 membered, and partly upon " the establishment of stable 

 connections between different groups of nervous elements." 

 I do not think that the view can be too strongly reprobated 

 which crudely supposes that the first of these physical con- 

 ditions is alone sufficient to explain all the facts of memory, 

 and therefore that a given remembrance is, as it were, stored 

 up in a particular cell, as a particular " impression " upon 

 the substance of that cell. On the contrary, as M. Kibot 

 shows, " Each of these supposed unities (memories) is com- 

 posed of numberless and heterogeneous elements ; it is an 

 association, a group, a fusion, a complexus, a multiplicity ; 

 . . . . Memory supposes not only a modification of 

 nervous elements, but the formation among them of determi- 

 nate associations for each particular act. We must not, how- 

 ever, forget that this is pure hypothesis — the best available 

 one, no doubt, but still not to be taken as implying that we 

 really know anything definitely concerning the physical sub- 

 stratum of memory." 



Profound, however, as our ignorance unquestionably is 

 concerning the physical substratum of memory, I think we 

 are at least justified in regarding this substratum as the same 

 both in ganglionic or organic, and in conscious or psycholo- 

 gical memory — seeing that the analogies between the two are 

 so numerous and precise. Consciousness is but an adjunct 

 which arises when the physical processes — owing to infre- 

 <|iiency of repetition, complexity of operation, or other causes — 

 involve what I have before called ganglionic friction. And 

 this view is confirmed by the large and general fact noted in 



• See "Concluding Observations on the Locomotor System of Medusss," 

 77,(7. Tram., l't. I, 1880 j and on "Modification of Excitability," 4c, 

 Proc. /.'."/. Snr. t Ifoa. 171 it ii • 1 211, Alto, Journal of Anatomy and Physio* 



logy, vul. x. Another equally j»oo(l instance of what mav be termed proto* 



■me- memory it to be found in the farts of the to-called "summation of 

 stimuli," which occur more or h>s in all excitable tissuec, ''., wherever 

 tiring protoplasm is ooncerned. These foot! are that if m suooeasion 'f 

 stimuli are applied to the excitable tissue, the latter becomes progressively 

 more and more quick, as well as moro und more energetic, in its response; 



each btiniulua leaves behind it an organic memory of ita occurrence. 



