48 THE STORY OF THE PLANTS. 



spine-like prickles. Indeed, the leaves and 

 branches are both prickly together, so that it is 

 difficult at first sight to discriminate between 

 them. But if you take a seedling gorse plant you 

 will find that in its early stages it still produces 

 trefoil leaves, like its clover-like ancestors; and 

 these leaves are almost exactly similar to those 

 of the common genista so much cultivated in 

 hot-houses. As the plant grows, however, the 

 trefoil leaves gradually give place to long and 

 narrow blades, and these in turn to prickly spines, 

 like the adult gorse-leaves. Hence we are justi- 

 fied in believing that the ancestors of gorse were 

 once genistas, bearing trefoil leaves; and that 

 later, through the action of natural selection, the 

 prickliest among them survived, till they acquired 

 their existing spiny foliage. In every case, in- 

 deed, young plants tend to resemble their earlier an- 

 cestors, and only as they grow up acquire their 

 later and more special characteristics. 



And now I must add one word about the ori- 

 gin of leaves in general. Very simple plants, we 

 saw, consist of a single cell, which is not merely 

 a leaf, but also at the same time a flower, a seed, 

 a root, a branch, and everything. In other words, 

 in very simple plants a single cell does rather 

 badly everything which in more advanced and 

 developed plants is better done by distinct and 

 highly-adapted organs. The whole evolution of 

 plants consists, in fact, in the telling off of par- 

 ticular parts to do better what the primitive cell 

 did for itself but badly. Above the very simple 

 plants which consist of a single cell come other 

 plants, which consist of many cells placed end on 

 end together, as in the case of the hair-like water- 



