10 OltGANS AND FUNCTIONS. 



plicated nervous system to supply the motive power, and 

 by means of which the animal is endowed with special 

 and acute senses, as those of sight, hearing, smell, taste, 

 and touch. 



Those animals, then, which exhibit the animal structure 

 and functions in their higher form, have the following 

 systems of organs, viz. : 



1. Digestive system. 



2. Absorbent " 



3. Circulatory " 



4. Respiratory " 



5. Secretory " 



6. Excretory " 



7. Motatory " 



8. Reproductive " 



9. Nervous " 



and each of these systems of organs, as stated above, per.- 

 forms its own peculiar and appropriate functions. 



The functions of animals are of two classes, those of or- 

 ganic or vegetative life, and those of animal life. 



The functions of Vegetative life are those of nutrition in 

 its largest sense, and of reproduction nutrition itself in- 

 cluding not only digestion, but also circulation, respiration, 

 etc. These are the functions which maintain life, and se- 

 cure the growth and multiplication of organized beings ; 

 and they are common to both plants and animals.* 



* If we enumerate all the separate acts of which the function of nutrition 

 consists, and by which it is directly and indirectly carried on, we must men- 

 tion at least absorption, digestion, circulation, respiration, exhalation, se- 

 cretion, excretion, and assimilation. Each of these acts must here be 

 briefly described. 



Absorption, in general terms, is the faculty or act by which organisms im- 

 bibe into their tissues the fluids which surround them, or which are contain- 



