38 OF HEALTH AND HUMAN NATURE- 



diet ; and has therefore acquired the name of second 

 nature. 



82. The more functions flourish simultaneously in the 

 body, the more considerable is its life ; and vice versd. 

 Hence life is greatest when the functions have attained 

 their highest perfection in adult age ; and least when 

 the functions, although very perfect, are fewer and more 

 sluggish, v. c. in the newly conceived embryo ; life is 

 for the same reason less vigorous during sleep than 

 during the opposite state. 



83. The functions have been long divided by physi- 

 ologists into four classes. This division, although not 

 unexceptionable nor exactly conformable to nature,* 

 may assist the memory, f 



1. The first class comprehends the vital functions, so 

 termed, because their uninterrupted and complete per- 

 formance is necessary to life. Such are the circulation 

 and respiration. 



2. The second comprehends the animal functions, by 

 which animals are chiefly distinguished from vegetables. 

 Such is the connection of the mind with the body, espe- 

 cially sense and muscular motion. 



3. The third is the natural, by means of which the 

 body is nourished. 



4. The fourth, the genital, intended for the propaga- 

 tion of the species. 



* See Platner, Qiupst. physiol. p. 31 ; and Versuch einer Anthropologie. 

 T. i. p. 100, 222 ; and my own remarks on the bad foundation of this division, 

 in the preface to my Enchiridion Anat. Comparatm, p. xi sq. 



f J. J. Bernhard, Versuch einer Vertheidigung der alien Eintheilung der 

 Functionen, und einer Classification des organisirten KSrper nach denstlben. 

 Erf. 1804. 8vo. 



