70 PHYSIOLOGY. 



other powers there are the brain seems to be the principal part 

 of the nervous system ; and its faculties, as we know, may re- 

 main when a limb, or several limbs, are entirely cut away. The 

 conclusion, therefore, more formally is " 



XCVII. From what is said (XCIL XCVI.), it is proba- 

 ble that the nervous and the inherent powers are somewhat 

 of the same nature ; and it is also probable, that in entire 

 and living bodies, both the nervous and inherent powers have a 

 constant dependence upon the animal (LXXXVII.) " This 

 animal power we suppose to be seated in the brain, and only 

 there seated. Whether you consider it as a sentient principle, 

 or a mechanical energy, it is probably the fundamental part of 

 the system, without which the functions cannot long remain. 



" So far I have laid a foundation for avoiding some false reason- 

 ings, and for introducing some which are more convincing with 

 respect to this subject. I must still try to carry the same views 

 a little farther ; and there is not a problem we would wish more 

 to solve than that of muscular contraction. This is a funda- 

 mental power in the system, and physiologists are commendable 

 for having attempted to explain it in different shapes ; but no 

 one is yet allowed to have had success, no view has been offer- 

 ed by anatomists and physiologists which is satisfying. But to 

 approach nearer, we must first reject the false suppositions for- 

 merly made."" 



XCVI II. The contraction of muscular fibres does not 

 depend immediately on the motion of the blood ; as it sub- 

 sists in many animals after all motion of the blood has ceased. 

 " There is no muscle that is not provided with a large 

 number of blood-vessels, which are distributed to every por- 

 tion of its fleshy belly, and closely accompany the moving 

 fibres, and which, in the opinion of many, do enter into their 

 composition. So it has been alleged that a muscle will become 

 paralytic, or lose its power of motion, not only when its nerve, 

 but also when its artery is tied ; and it has been from this ex- 

 periment concluded, that the influx of arterial blood is as neces- 

 sary as the nervous power ; but this supposition, and all the 

 theories which have been founded upon it, are suspicious, when 

 we observe that this is not exactly the fact, for the muscle is 

 rendered paralytic, not immediately, but a long time afterwards, 



