Memory. 



When, from disuse, it is no longer excitable, it has forgotten. Its ex- 

 citement while under stimulation is called its erection, or erethism, and 

 is, in fact, its remembrance. 



If the foregoing definitions are correct, and we shall have further 

 proofs that they are, there is no difference in principle between the mem- 

 ories and recollections of the reflex centers and those called excito-mo- 

 tor, automatic, sensori-motor or ideo-motor. We are apt to associate 

 remembrance with consciousness ; but we shall see further on that at 

 least, remembrance is not in any way founded upon consciousness. Since 

 consciousness, or at least the most important consciousness, appears to 

 arise in the ideo-motor centers in the cerebrum, the habit of associating 

 it with remembrance leads to an ill defined inference that the latter is a 

 function of the cerebrum alone. But as there is no necessary connec- 

 tion between the two, the inference is entirely unfounded, and is, in 

 fact, false. The difference between the remembrance of the spinal cord 

 and that of the cerebrum, is one of degree and detail, not principle. In 

 all cases it consists in the re-erection of cells which have been erected 

 by a previous stimulation. In the case of the spinal reflex cells, there 

 is only one sort of stimulation which will produce their re-erection, and 

 that is the same external sensory touch impression that differentiated 

 and erected them in the first place ; and the quantity or quality of their 

 memory is measured by the superior ease and facility with which they 

 yield to the stimulation now, as compared with their inertia and reluc- 

 tance when agitated the first time. 



The memory of the cerebral cells is of precisely the same nature aa 

 that of the spinal cells. But the cerebral cells have connections in all 

 directions with each other, and they are stimulated through these con- 

 nections from many original sources, although before a cell is re-erected 

 the stimulation doubtless takes the same form that was necessary to 

 erect it in the first place. At any rate, an ideo-motor cell may be re- 

 stimulated by an associated cell, of which there may be many, as well 

 as by a new sensory impression from the environment ; while the spinal 

 reflex cell is restimulated only by the external sensory impression. Not 

 only are the memories of cerebral sensory cells liable to be aroused by 

 the action of associated cells, but the motor action, to which such stim- 

 ulation might lead, is equally liable to become, by the same sort of in- 

 terference, stronger or weaker, and to be diverted or deflected, and take 

 a route not taken before. The motor action of the spinal reflex cell is 

 little liable to any such accidents. As the revival of its memory is ef- 

 fected by a uniform sensory stimulus, so there is a sameness in the re- 

 sulting motor action. 



The view of memory given here makes it necessary to distinguish be- 

 tween conscious and unconscious memories. Commonly, only the for- 



