14 INTRODUCTION. . 



When condensed., this substance forms those laminse called 

 membranes ; the memhranes; rolled into cylinders, form those 

 more or less ramified tubes named vessels; the filaments called 

 fibres are resolved into it, and bones are nothing but the same 

 thing indurated by the accumulation of earthy 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 ^natter 

 to its organic molecules ; to the naked eye, it appears like a 

 sort of soft bouillie, consisting of excessively small globules ; it 

 is not susceptible of any apparent 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 sentient organs are, essentially, mere fasciculi of its rami- 

 fications. 



The fleshy or muscular fibre 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 nerve. 



The muscles, direct organs of voluntary motion, are mere 

 bundles of fleshy fibres. All vessels and membranes which 

 have any kind of compression to execute are armed with these 

 fibres. They are always intimately connected with nervous 

 threads, but those which belong to the purely vegetative func- 

 tions contract, without the knowledge of the me, so that, al- 

 though 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 fibrine and gelatine, almost 

 prepared to contract and to assume the forms of membranes 



