THE MOKPHOLOGICAL COMPOSITION OF PLANTS. 65 



there comes to be a more marked contrast between it and the 

 petioles, severally carrying a leaf each.* 



194. When, in the course of the process above sketched 

 out, there has arisen such community of nutrition among the 

 fronds thus integrated into a series, that the younger ones 

 are aided by materials which the older ones have elaborated; 

 the younger fronds will begin to show, at earlier and earlier 

 periods of development, the structures about to originate 

 from them. Abundant nutrition will abbreviate the intervals 

 between the successive prolifications ; so that eventually, 

 while each frond is yet imperfectly formed, the rudiment of 

 the next will begin to show itself. All embryology justifies 

 this inference. The analogies it furnishes lead us to expect 

 that when this serial arrangement becomes organic, the 

 growing part of the series will show the general relations of 

 the forthcoming parts, while they are very small and un- 

 specialized. What will in such case be the appearances they 

 assume? We shall have no difficulty in perceiving what it 

 will be, if we take a form like that shown in Fig. 92, and 

 dwarf its several parts at the same time that we generalize 

 them. Figs. 100, 101, 102, and 103, will show the result; 



t03 



and in Fig. 104, which is the bud of a dicotyledon, we see 

 how clear is the morphological correspondence: a being the 

 rudiment of a foliar organ beginning to take shape; 6 being 

 the almost formless rudiment of the next foliar organ; and 



* Since this paragraph was put in type [this refers to the first edition], 

 I have observed that in some varieties of Cineraria, as probably in other 

 plants, a single individual furnishes all these forms of leaves all gradations 

 between unstipulated leaves on long petioles, and leaves that embrace the 

 axis. It may be added that the distribution of these various forms is quite 

 in harmony with the rationale above given. 

 51 



