CHAP. I The Wealth of Life 13 



There is of course no doubt as to the fact that some forms 

 of life are more complex than others. It requires no faith 

 to allow that the firstlings or Protozoa are simpler than 

 all the rest ; that sponges, which are more or less loose 

 colonies of unit masses imperfectly compacted together, are 

 in that sense simpler than jellyfish, and so on. The animals 

 most like ourselves are more intricate and more perfectly 

 controlled organisms than those which are obviously more 

 remote, and associated with this perfecting of structure there 

 is an increasing fulness and freedom of life. 



We may arrange all the classes in series from low to high, 

 from simple to complex, but this will express only our ;most 

 generalised conceptions. For within each class there is 

 great variety, each has its own masterpieces. Thus the 

 simplest animals are often cased in shells of flint or lime 

 whose crystalline architecture has great complexity. The 

 simplest sponge is little more than a double-walled sack 

 riddled by pores through which the water is lashed, but 

 the Venus' Flower-Basket (Euplectelld), one of the flinty 

 sponges, has a complex system of water canals and a 

 skeleton of flinty threads built up into a framework of 

 marvellous intricacy and grace. The lowest insect is not 

 much more intricate, centralised, or controlled than many 

 a worm of the sea-shore, but the ant or the bee is a very 

 complex self-controlled organism. More exact, therefore, 

 than any linear series, is the image of a tree with branches 

 springing from different levels, each branch again bearing 

 twigs some of which rise higher than the base of the branch 

 above. A perfect scheme of this sort might not only express 

 the facts of structure, it might also express our notions of 

 the blood-relationships of animals and the way in which we 

 believe that different forms have arisen. 



But the wealth of form is less varied than at first sight 

 appears. There is great wealth, but the coinage is very 

 uniform. Our first impression is one of manifold variety ; 

 but that gives place to one of marvellous plasticity when 

 we see how structures apparently quite different are redu- 

 cible to the same general plan. Thus, as the poet Goethe 

 first clearly showed, the seed-leaves, root-leaves, stem-leaves. 



