xiii CREATION AND EVOLUTION 141 



dichotomum, and another of homomorphic species, including 

 Z. affine, simplex, and nutans. We have thus two very 

 obvious ways of arranging or dassifyi7i^ the species of 

 Zoothamnium, and the question arises— which of these, if 

 either, is the right one ? Is there any standard by which 

 we can judge of the accuracy of a given classification of 

 these or any other organisms, or does the whole thing depend 

 upon the fancy of the classifier, like the arrangement of 

 books in a library ? In other words, are all possible classi- 

 fications of living things more or less artificial, or is there 

 such a thing as a natural classification ? 



Suppose we were to try and classify all the members of a 

 given family — parents and grandparents, uncles and aunts, 

 cousins, second cousins, and so on. Obviously there are a 

 hundred ways in which it would be possible to arrange 

 them — into dark and fair, tall and short, curly-haired and 

 straight-haired and so on. But is is equally obvious that all 

 these methods would be purely artificial, and that the only 

 natural way, i.e., the only way to show the real connection of 

 the various members of the family with one another would 

 be to classify them according to blood-relationship, in other 

 words to let our classification take the form of a genea- 

 logical tree. 



It may be said — what has this to do with the point under 

 discussion, the classification of the species of Zoothamnium ? 



There are two theories which attempt to account for the 

 existence of the innumerable species of living things which 

 inhabit our earth : the theory of creation and the theory of 

 evolution. 



According to the theory of creation, all the individuals of 

 every species existing at the present day— the tens of 

 thousands of dogs, oak trees, amoebae, and what not — are 

 derived by a natural process of descent from a single indi- 



