Consciousness. 969 



ments, as nerves or ganglions. Like the vibratory motion of the 

 spring, it may be regarded as the vibratory motion of a particular por- 

 tion of elastic matter arranged in a suitable shape. Probably an in- 

 strument like an open flute would be a better simile than a spring. For 

 the form of the cell containing the ethereal substance, whose motion is 

 sensation, must govern the form of the portion of this substance which 

 is, in each particular instance, detached and set off from the general 

 mass. Form, in a vibrator}^ mass, is of essential importance to the 

 quality of its vibrations. It is of equal importance, to the movement 

 set up in any sort of instrument or machine. As we have seen all 

 along, the organs concerned in the performance of any sort of organic 

 function, are subject to modification by the action upon them of the 

 force by which they are operated, and this generally means a differentia- 

 tion and development of the organ, increasing its facility and thorough- 

 ness of function. Examples of this are found in the development of 

 the highly contractile muscle from inertly contractile protoplasm ; of 

 the ocellus from a pigment spot, and the eye from the ocellus ; of the 

 four bones of the ear from the columella, of wings from paddles, &c. 

 Following this analogy, we may be assured that the function of sensa- 

 tion has undergone modification through the development of the mate- 

 rial apparatus whose motion it is. . If we have a mass of steel in a 

 solid lump, it possesses elasticity, and if we strike it with a hammer, 

 the hammer will bound off, and the steel itself be set to vibrating in a 

 slight and subdued manner. If the shape of the mass be changed to 

 form a rod, its elasticity causes it to vibrate in a different manner, and 

 more freely, and at a smaller expenditure of antecedent force. 



This sort of development has taken place in regard to organs of sen- 

 sation. Undoubtedly those animals which have a better general devel- 

 opment, also have more sensitive organs of sensation, and a greater 

 number of them. They would necessarily become developed in approx- 

 imately the same proportion. 



Like any other function, sensation becomes more acute and vivid by 

 action ; so that the of tener the organ of a particular sensation is re- 

 erected by recollection, the more real and vivid the recollected sensation 

 of the image, idea or thought of any kind, becomes. Thus, if we wish 

 to retain in memory a poem, an oration, the circumstances of an event, 

 or anything of the sort, the oftener it is called up, the more indelibly 

 does it become impressed ; that is, the organ involved is stimulated to 

 perform its normal function in greater force, with less expenditure of 

 antecedent energy ; in other words, with less effort. But there is an ap- 

 parent exception to this in the very different effects ordinarily resulting 

 in the case of recollection of highly emotional sensations. Extremely 

 pleasurable sensations are made more intense by their frequent recall, not 



