Neural Integration 1()9 



well expressed bj Donaldson : "Isolated groups of nerve- 

 cells do not occur. Indeed, a group of nerve-cells discon- 

 nected from the other nerve-tissues of the body, as nuiscles 

 or glands are disconnected, would be witliout j)hvsiological 

 significance. It is desirable, therefore, to emphasize the 

 fact that by dissection the nervous system is found to l)o 

 connected throughout its entire extent." '' 



I would ask the reader to consider these statements in the 

 light of the cellular conception of the organism maintained 

 in this volume and especially dwelt upon in the chapters on 

 the cell-theory, namely, that the true way of viewing the 

 organism is not as being built up of cells in the sense of 

 having been constructed by the bringing together of pre- 

 viously isolated cells, as a brick house is built up of bricks ; 

 but rather as being composed of cells through resolving 

 itself into these as it increases in size and differentiates 

 itself into its organs and functions. With such a concep- 

 tion Sherrington's formulation, based on the findings of 

 vast observational and experimental research on the struc- 

 ture and action of the nervous system, is in perfect accord. 

 If we see in the completed nervous system a complex 

 mechanism developing as a unit subservient at all stages to 

 the needs of the organism as a whole, the myriads of reflex- 

 arcs then present themselves as final, as end-stages in the 

 differentiation and not as initial states ; and the universal 

 organic and functional connection with one another, affirmed 

 in the quotation, would be just what we might expect. 



If, on the other hand, the integral nervous system 

 were built up in a literal sense, that is, by the actual coming 

 into connection with one another of previously isolated 

 simjole reflex-arcs, such arcs ought to be demonstrable botli 

 in the ontogeny of higher animals and in the adults of the 

 lower metazoa. 



No one should be beguiled into the notion that the readily 

 observed facts of ontogeny of the nervous system, the vari- 



