General Principles of Physiology. 103 
We have now taken a view of the phenomena of the various 
powers of the animal body necessary to the preservation of life. 
As we have found the muscular independent of the nervous power, 
yet influenced byit, we have found the nervous independent of the 
sensorial power, yet in like manner influenced by it; we can 
withdraw the sensorial without destroying the nervous power,.as 
we can withdraw the nervous without destroying the muscular 
power ; butin the entire animal, as the muscular obeys the nerv- 
ous, the nervous obeys the sensorial power, and they are all so 
connected that the existence of each indirectly depends on that 
of the others. 
On the analogy which exists between the contraction of the 
muscular fibre and the coagulation of certain fluids, I have al- 
ready had occasion to make some observations. Can we refer 
the phenomena of the sensorial and nervous powers to any more 
general principle? 
As the properties of the vital principle do not differ from those 
of inanimate matter merely in degree or by any other modifi- 
cation, but have nothing incommon with them, it follows, that 
when parts endowed with this principle affect each other only 
by their vital properties, the resuit must be such as bears no ana- 
logy to any of the properties of inanimate matter; and, conse- 
quently, that in all processes which have any such analogy, one 
of the agents must operate by the properties of this matter. 
We have seen that the characteristic difference in the sensorial 
and neryous functions is, that the former bear no analogy, the 
latter a very striking one, to those properties. On the other 
hand, we see the organs of the nervous system impressed by ex- 
ternal objects, those of the sensorial system only through other 
vital parts. The nervous system is evidently the connecting link 
between the sensorium and the world which surrounds-us. It 
consists of parts endowed with the vital principle, yet capable of 
acting in concert with inanimate matter; receiving impressions 
fromit, and ifthe position just stated be correct, capable of im- 
pressing it; for there can be no stronger analogy than that which 
subsists between the secreting processes effected by the influence 
