Consciousness. 975 



by observation of the increased facility of brain action generally, includ- 

 ing the sharpening and quickening of the sensations by use. The fact 

 of such improvement in sensibility and therefore in consciousness by 

 use, puts this class of functions and their organs upon the same ph\ Bio- 

 logical basis as the muscular, vascular, visceral and osseous systems and 

 argues for them the like e\olution and specialization from the most 

 elementary beginnings. Judged by these analogies, we should be led 

 to suppose that the essential basis of sensibility resides in a diffused and 

 nebulous condition in tissues both animal and vegetable, and possibly in 

 elemental bodies, as phosphorus, perhaps. The conception is, that sen- 

 sation is a particular tone or scale of tones of some sort of motion of the 

 Hln-r. Such motion takes place in portions of the ether, of a certain den- 

 sity, that are cut off from the general mass and shut up in cells of dense 

 matter of particular form and size. Whenever matter is organized in 

 such a way that it contains such molecular interstices, the contained ether, 

 if of the requisite density and agitated by stimulations of a proper tone, 

 becomes sensible ; that is, the motion set up in it is sensation. In un- 

 organized or poorl} T organized bodies in which there are few or no ner- 

 vous pathways, we may suppose that the stimulation from the outside 

 is largely consumed by friction in getting at the enclosed spaces so that 

 the agitation set up in them is in small amplitude and of a feeble and 

 subdued nature. In the lowest organisms, such as amoeba, monera, 

 &c. , the sensibility is confined to such as can be aroused by touch and 

 light, ajid is scattered . through the tissues. In plants it is also con- 

 fined to touch and light, but to a certain extent specialized in the roots 

 and leaves. The forming and shaping of the spaces which in organized 

 bodies become cells, are due without doubt to the action of the exter- 

 nal energy, and the tendency of this action would be to develop these 

 organs in the parts most accessible to it. Thus it is that cells sensitive 

 to touch are found in the roots of plants, and that those sensitive to 

 light occur in the leaves. The sensibilities become, in all organisms (to 

 the extent to which they occur), elements for the direction of the motor 

 energies will formers. This puts them in an intermediate relationship 

 between the external energies that cause them, and the motor parts 

 whose action they govern, and leads to the aggregation of their cells in 

 ganglions in intermediate positions. 



At first there is no separation or distinction between the functions of 

 sensibility and kinetic impression. By kinetic impression, in this con- 

 nection, I mean those impressions made upon bodies both organic and 

 inorganic, by radiant and other forms of molecular motion, whereby 

 molecular changes ( other than sensibilit} T ) are wrought in the bodies. 

 Examples of this action are given in chapters 42 and 43. The chemical 

 and other physical changes produced by light and heat in inorganic 



