I04 Flowers and their Pedigrees. 



and type than all the other leaves which come after 

 them. In the language of science they are less 

 .specialised ; they represent an earlier and undevel- 

 oped form of leaf — nature's rough sketch, so to speak, 

 while the later foliage represents the final improve- 

 ments introduced with time, and perfected by the 

 action of natural selection. 



These large oval leaves which you see in the 

 seedling are mere general models or central ideas of 

 what a leaf should be ; they are quite unadapted to 

 any one special or definite situation. They are not 

 divided into many little separate leaflets, or prolonged 

 into points and angles, or gracefully vandyked round 

 the edges, or beautifully cut out into lacelike patterns, 

 or armed at everj- rib with stout defensive prickles, 

 like many other leaves that you know familiarly. 

 Their outline is quite simple and unbroken ; they 

 preserve for us still the -extremely plain ancestral 

 form from which such different leaves as those of the 

 horse-chestnut, the oak, the clover, the milfoil, the 

 parsley, and the holly are ultimately derived. An 

 expanded oval, something like this, is the prime 

 original, the central point from which everj- variety of 

 foliage first set out, and from which they have all 

 diverged in various directions, according as different 

 circumstances favoured or checked their development 



