General Principles of Physiology. 109 
of its most characteristic properties the influence of the 
nervous system resembles. Lastly, we know that an agent of the 
same nature with that of which we now speak, electricity, is in 
some animals capable of being collected and applied by the 
organs of the nervous system. 
When from the nervous and muscular we turn to the sensorial 
functions, we perceive results which have lost all analogy to 
those of inanimate matter. They have only an indirect effect 
in maintaining animal life, and are excited by no impressions 
but those communicated through the nervous system, and con- 
sequently are the results of living parts acting on each other. 
Hence it is, that they are the first functions which cease when 
the vital power begins to fail. In the nervous and muscular 
functions an inanimate agent excites the languid powers of life. 
In the sensorial functions, the functional power and the stimulus 
which excites it, being equally vital powers, fail together. } 
When the nature of the sensorial functions is kept in view, 
we cannot be surprised that the attempts to refer them to 
a more general principle have proved so futile. To what 
other principle shall we refer the effects of the vital parts 
of animals on each other, when it is in animals alone 
that such parts ever influence each other? Even in vegetable 
life we find nothing analogous to the sensorial functions. All 
its processes bear the same analogy to the properties of inanimate 
matter, which we observe inthe functions of the nervous and 
muscular systems of animals, and are, therefore, the results of 
inanimate agents acting on living matter*. Much less can we 
look for any analogies of this kind in inanimate nature itself, 
Such reveries may please as the creations of the poet, but 
admit not of serious discussion. We are charmed with the 
flights of Lucretius, but we see only the perversion of philosophy 
in the reasonings of Hartley. 
If the foregoing inferences from the various experiments 
* It is here worthy of remark, that many phenomena render it probable 
that there is a continual passage of the electric influence througk plants, 
to which both their form and position are peculiarly adapted, 
