XIII. ] THE BIOLOGICAL SCIENCES AND MEDICINE. 341 



general principles of the animal machine to suppose 

 that none of its effects are produced from any 

 mechanical principle whatever ; and that every effect 

 is produced from an action in the part ; which action 

 is produced by a stimulus upon the part which acts, 

 or upon some other part with which * this part 

 sympathises so as to take up the whole action" 

 (Lc. p. 152). 



And Hunter is as clear as Wolff, with whose work 

 he was probably unacquainted, that "whatever life is, 

 it most certainly does not depend upon structure or 

 organisation" (I.e. p. 114). 



Of course it is impossible that Hunter could have 

 intended to deny the existence of purely mechanical 

 operations in the animal body. But while, with 

 Borelli and Boerhaave, he looked upon absorption, 

 nutrition, and secretion as operations effected by 

 means of the small vessels, he differed from the 

 mechanical physiologists, who regarded these opera- 

 tions as the result of the mechanical properties of the 

 small vessels, such as the size, form, and disposition 

 of their canals and apertures. Hunter, on the con- 

 trary, considers them to be the effect of properties of 

 these vessels which are not mechanical but vital. 

 " The vessels," says he, " have more of the polypus in 

 them than any other part of the body," and he talks 

 of the " living and sensitive principles of the arteries," 

 and even of the "dispositions or feelings of the arteries." 

 " When the blood is good and genuine the sensations 

 of the arteries, or the dispositions for sensation, are 

 agreeable. ... It is then they dispose of the blood 



