12 INTRODUCTION. 



muscles the orders of the will. It constitutes the greater portion of the 

 Mrain and the spinal marrow, and the nerves which are distributed 

 to all the sentient organs are, essentially, mere fasciculi or bundles of 

 its ramifications. The fleshy or muscular Jibre is a peculiar sort of 

 filament, whose distinctive 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 nerves. 



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 the nervous threads, but those which belong to 

 the purely vegetative functions, contract without the knowledge of the 

 individual, 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 Jibrine, 

 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 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 con- 

 tains fibrine 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 combination, which is found in many animal fluids and 

 solids, called albumen, whose characteristic property is that of coagulat- 

 ing in boiling water. Besides these, the blood contains almost every 

 element which may enter into the composition of the body of each 

 animal, such as the lime and phosphorus which harden the bones of 

 vertebrated animals, the iron from which the blood and various other 

 parts receive their colour, the fat or animal oil which is deposited in the 

 cellular substance to supply it, &c. All the fluids and solids of the 

 animal body are composed of chemical elements found in the blood, and 

 it is only by possessing a few elements more or less, that each of them 

 is distinguished ; whence it is plain, that their formation entirely 

 depends on the subtraction of the whole or part of one or more elements 

 of the blood, and in some few cases on the addition of some element 

 from elsewhere. 



These operations, by which the blood nourishes the fluid or solid 

 matter of all parts of the body, may assume the general name of secre- 

 tions. This name, however, is often appropriated exclusively to the 



