158 Journal of Comparative Neurology. 



be sure, but not by a direct migration to their ultimate site, but 

 rather by the formation of germinative areas at the tip and 

 sides of the organ whence, by a species of migration, they 

 reached the entire ectal surface, there to multiply by mitosis 

 until the requisite supply had been produced. {^Jour. Comp. 

 Neurol. Vol. I, No. i.) In other papers {Wood's Ref. Hand- 

 book, Suppl.) the further process was followed until the newly 

 formed cells, sinking below the surface and still continuing to 

 proliferate, reach their permanent places. Though these dis- 

 coveries were treated contemptuously by certain critics, they 

 have been re-affirmed and verified by a number of independent 

 observers. The writer has also suggested a somewhat similar 

 process for the cells of the cerebrum and, while the details of 

 the process remain to be worked out, there seems to be no 

 doubt that there is a similar segregation of proliferating areas 

 or germinal masses which remain up to a late period capable of 

 producing new cells to be interpolated in the cortical series. 



This gives rise to a means for construing the otherwise in- 

 explicable fact that, although the neurocytes are continually 

 degenerating and disappearing, the essential elements of mem- 

 ory remain unchanged. If consciousness consisted in the re- 

 actions of various cells or groups of cells, then there would be 

 a footing for the conventional theory of reproduction as a re- 

 vival of vestiges in the several cells previously affected. But 

 from the equilibrium theory it appears that the state of equi- 

 librium is the important thing, whether that state be the result 

 of the participation of one set of elements or of another whose 

 neural resultant would be the same. Thus, while certain cells 

 of a given cortical complex are disappearing, other cells are 

 entering it and gradually assuming the exact organic constitu- 

 tion adapted to complete their participation in the activity of 

 that complex. By such a process of gradual assimilation and 

 of substitution we conceive that the persistence of memory is 

 to be explained. Still further it seems plain that what we now 

 know of the gradual loss of the finer processes of the dendrites 

 etc., stands in harmony with the observed fact that the earHer, 

 less highly correlated, memories are the last to be lost. 



