280 PHYSICAL EXPRESSION. 



ject. " The seed swells ; " this is due to " enlarge- 

 ment of each cotyledon" (trophic). "The radicle 

 grows and protrudes " (trophic action). In this 

 example of growth, the ratio of the quantity of 

 growth in the testa and the radicle is not constant 

 as germination proceeds. Growth occurs more 

 rapidly in the radicle than in other parts. The 

 covering, or testa, bursts as a secondary result of 

 growth of the cotyledons ; the rupture is due to the 

 absence of equal proportional development in 

 embryo and testa. The plumule protrudes ; rapid 

 growth now occurs here (quantity of trophic action). 



We may now inquire more closely as to each of 

 these trophic processes. It is obviously desirable 

 whenever we speak of a function, to know ex- 

 actly what is the subject displaying that function. 

 When we speak of the trophic function displayed 

 in a bean as the radicle elongates, we do not mean 

 to say that all parts are nourished to cause the 

 radicle to grow, though this may be true : clearly 

 we mean that the radicle displays the trophic 

 function ; the radicle is the subject, the vital action 

 in it is said to be "trophic action." The question 

 now arises, is this subject one and indivisible, or is 

 it an assemblage of cells ? If the latter, do all the 

 cells composing the radicle go through a similar 

 series of trophic action ? 



The regular circumnutation of the radicle in- 

 volves numerous minor subjects, the cells of the 

 radicle undergoing a regular series of trophic 

 actions. It is also true that the nutrition produces 

 partly trophic, partly kinetic, expression (see 

 p. 283). 



