10 NUTRITION AND REPRODUCTION 



In the processes of nutrition and reproduction, 

 we perceive the passage of matter from the state of 

 motion to that of rest (static equilibrium) ; under 

 the influence of the nervous system, this matter 

 enters again into a state of motion. The ultimate 

 causes of these different conditions of the vital force 

 are chemical forces. 



The cause of the state of rest is a resistance, 

 determined by a force of attraction (combination), 

 which acts between the smallest particles of matter, 

 and is manifested only when these are in actual 

 contact, or at infinitely small distances. 



To this peculiar kind of attraction we may of 

 course apply different names ; but the chemist calls 

 it affinity. 



The cause of the state of motion is to be found 

 in a series of changes which the food undergoes in 

 the organism, and these are the results of processes 

 of decomposition, to which either the food itself, or 

 the structures formed from it, or parts of organs, 

 are subjected. 



The distinguishing character of vegetable life is a 

 continued passage of matter from the state of mo- 

 tion to that of static equilibrium. While a plant 

 lives, we cannot perceive any cessation in its growth ; 

 110 part of an organ in the plant diminishes in size. 

 If decomposition occur, it is the result of assimila- 

 tion. A plant produces within itself no cause of 

 motion ; no part of its structure, from any influence 

 residing in its organism, loses its state of vitality, 



