34 MEMOIR OF BARON HALLER. 



sensibility of the several structures of the animal 

 machine, and the degree of sensibility possessed by 

 each. The skin is stated to be more sensible than 

 any other ; then the muscular fibre, both of which, 

 however, derive this property from the nerves ; and 

 these being the source of the sensibility of the other 

 parts, are themselves, of course, exceedingly sensible. 

 Again the marrow, the bones, the internal viscera, 

 &c. to which this property had been generally very 

 freely conceded, were found to be wholly destitute 

 of it. So that all the facts on this point are summed 

 up in the following sentence : " The sensible parts 

 of the body are the nerves themselves, and those 

 parts to which they are distributed in the greatest 

 abundance. In fact, the nerves alone are sensible 

 of themselves, and their whole sensibility resides in 

 their medullary part, which is a production of the 

 internal substance of the brain, to which the pia~ 

 mater furnishes a covering." 



The author next proceeds to the subject of irri- 

 tability , which he demonstrates to be so different 

 from sensibility, that the most irritable parts are not 

 at all sensible, and the most sensible are not irritable. 

 He endeavours in detail to prove both of these pro- 

 positions by facts, and then to demonstrate that 

 irritability does not depend upon the nerves, but 

 upon the inherent constitution of the parts in which 

 it resides. After this, the whole variety of struc- 

 tures is in the same way examined as it respects 

 their irritability, beginning with the nerves, which 

 are proved to be not at all irritable ; no more is the 



