INTRODUCTION. ll 
named vessels; the filaments, called fibres, are resolved into it; and bones 
are nothing but the same thing indurated by the accumulation of earth- 
ly particles. 
The cellular substance consists of a combination well known as gelatine, 
characterised by its solubility in boiling water, and forming, when cold, a 
trembling jelly. 
We have not yet been able to reduce the medullary matter to its or- 
ganic molecules; to the naked eye, it appears like a sort of soft bouillie, 
consisting of excessively small globules; it is not susceptible of any appa- 
rent motion, but in it resides the admirable power of transmitting to the 
ME the impressions of the external senses, and conveying to the muscles 
the orders of the will. It constitutes the greater portion of the brain and 
the spinal marrow, and the nerves which are distributed to all the sen- 
tient organs are, essentially, mere fasciculi of its ramifications. 
The fleshy, or muscular fibre, is a peculiar sort of filament, whose distinc- 
tive property, during life, is that of contracting when touched or struck, 
or when it experiences the action of the will through the medium of the 
nerve. 
The muscles, direct organs of voluntary motion, are mere bundles of 
fleshy fibres. All vessels and membranes which have any kind of com- 
pression to execute are armed with these fibres. They are always inti- 
mately connected with nervous threads, but those which belong to the 
purely vegetative functions contract, without the knowledge of the mr, so 
that, although the will is truly a means of causing the fibres to act, it is 
neither general nor unique. 
The fleshy fibre has for its base a particular substance called fibrine, 
which is insoluble in boiling water, and which seems naturally to assume 
this filamentous disposition. 
The nutritive fluid or the blood, such as we find it in the vessels of the 
circulation, is not only mostly resolvable into the general elements of the 
animal body, carbon, hydrogen, oxygen, and azote, but it also contains fi- 
brine and gelatine, almost prepared to contract and to assume the forms of 
membranes or filaments peculiar to them, all that is ever wanted for their 
manifestation being a little repose. The blood also contains another com- 
bination, which is found in many animal fluids and solids, called albumen, 
whose characteristic property is that of coagulating in boiling water. Be- 
sides these, the blood contains almost every element which may enter into 
the composition of the body of each animal, such as the lime and phospho- 
rus which harden the bones of vertebrated animals, the zron from which it 
and various other parts receive their colour, the fat or animal oil which is 
deposited in the cellular substance to supple it, &c. All the fluids and 
solids of the animal body are composed of chemical clements found in the 
