2 THE WORLD OF LIFE 



externally and internally he could find no resemblance what- 

 ever to his own body; to crabs and winged insects, to land- 

 shells and sea-shells, and ultimately to everything which by 

 moving and feeding, by growdng and dying, showed that it 

 was, like himself, alive. Here, probably, he would rest for 

 awhile, and it might require several generations of incipient 

 philosophers to extend the great generalisation of " life " to 

 that omnipresent clothing of the earth's surface produced by 

 the infinitely varied forms of vegetation. The more familiar 

 any phenomenon is — the more it is absolutely essential to 

 our life and well-being — the less attention we pay to it and 

 the less it seems to need any special explanation. Trees, shrubs, 

 and herbs, being outgrowths from the soil, being incapable of 

 any bodily motion and usually exhibiting no indications of 

 sensation, might w^ell have been looked upon as a necessary 

 appendage of the earth, analogous to the hair of mammals or 

 the feathers of birds. It was probably long before their end- 

 less diversity attracted much notice, except in so far as the 

 fruits or the roots were eatable, or the stems or foliage or bark 

 useful for huts or clothing ; wdiile the idea that there is in them 

 any essential feature connecting them wdth animals and en- 

 titling them to be classed all together as members of the great 

 ^vorld of life would only arise at a considerably later stage 

 of development. 



It is, in fact, only in recent times that the very close resem- 

 blance of plants and animals has been generally recognised. 

 The basis of the structure of both is the almost indistinguish- 

 able cell ; both grow from germs ; both have a varied life-period 

 from a few" months to a maximum of a few" hundreds of vears : 

 both in all their more highly organised forms, and in many of 

 their lower types also, are bisexual ; both consist of an immense 

 variety of distinct species, which can be classified in the same 

 way into higher and higher groups; the laws of variation, 

 heredity, and the struggle for existence apply equally to both, 

 and their evolution under these laws has gone on in a parallel 

 course from the earliest periods of the geological record. 



