VI.] 



LEA VES OF SEEDLINGS. 



141 



shaped leaf is the older form from which the palmate 

 type has been gradually evolved. Let us see whether 

 we can find any evidence bearing on this question in 

 what may be called the embryology of plants. The 

 Furze, with its spiny prickles, belongs to a group of 

 plants which, as a general rule, have trifoliate or 

 pinnate leaves. Now, if we examine a seedling Furze 

 (Fig. 91), we shall find that the cotyledons are 



FIG 91. FURZE (.Ulex). Seedling. 



succeeded by several trifoliate leaves, with ovate 

 leaflets. These gradually become narrower, more 

 pointed, and stiffer, thus passing into spines. Hence 

 we can hardly doubt that the present Furze is 

 descended from ancestors with trifoliate leaves. I 

 have already referred to other cases in which the 

 young plants throw light on the previous condition 

 of the species (ante, p. 120). 



