€02 Mr. Charles Merrier [May 3, 



the whole material universe. Every modification of form, whether 

 gross or molecular, in every material body, has arisen under the 

 stress of incident motion, and may be regarded as the structural 

 memory of that experience. Confining our attention to organised 

 bodies only, it is evident that the form which every organism 

 assumes, whether in external contour or in internal organisation, is the 

 structural memory which it has retained of the experiences that itself 

 and its ancestors have undergone. Extravagant as the statement 

 appears at first sight, it needs but little consideration to show that it 

 is literally true, and true also that day by day, hour by hour, and 

 moment by moment, the organism, and especially its nervous system, 

 is still acquiring structural memories under the experience of inci- 

 dent motion. So long as the structure thus modified remains func- 

 tionally inactive, so long the conscious memory of the experience 

 remains in abeyance. The moment that activity of function takes 

 place in the tissue, at that moment a state of consciousness arises 

 which is the counterpart of the state that occurred on the formation 

 of the structural memory, and that is the conscious memory of that 

 experience. 



The memories of experiences that are registered in the nervous 

 system may be compared with the memories of aerial vibration that 

 are registered on the waxen cylinder of the phonograph. In both 

 cases the structural change left by the experience bears no resem- 

 blance to the experience under which it arose. In both cases the 

 structural change may remain for an indefinite time inert and passive, 

 a mere change of shape, unaccompanied by any process which repeats 

 or recalls the experience during which it was formed. In both 

 cases the modified structure may be started into active function at 

 any moment by appropriate addition of motion ; and in both cases it 

 is then, and then only, that an experience is reproduced which is the 

 more or less accurate counterpart of the experience under which the 

 alteration of structure took place. 



Each of the four forms of memory that have been enumerated 

 demands separate consideration. 



Structural or Statical Memory. — Upon the structural change 

 produced by an experience depend the endurance and the faithful- 

 ness of the conscious memory ; indeed, when we speak of the 

 endurance of a conscious memory, we use a figure of speech, for the 

 conscious memory does not endure. What endures is the structural 

 memory alone, and what is called the endurance of the conscious 

 memory is the enduring liability of the structural memory to become 

 active and to be attended by consciousness. Keeping this distinction 

 in our minds, it is evident, from the account already given of struc- 

 tural memory, that the endurance of a memory depends upon the 

 amount of set that is impressed by the experience on the tissue, and 

 that this differs much, not only as to different experiences, but as to 

 diflerent parts of the same experience. Of every distortion of tissue 

 that is produced, for instance, by an impression on the senses, somo 



