Living Things are Distinguished by Form 55 



tions of relationship — gradually force themselves upon our 

 attention. 



Let us, then, look at the workings of living things in 

 general by attempting to contrast them with non-living 

 things. 



hiving Things are Distinguished by Form 



The plants and animals with which we are most familiar 

 are commonly recognized as belonging each to a particular 

 species or kind. We recognize the group in which we would 

 place a given individual by the general form. We can recog- 

 nize a particular kind of tree or a particular kind of shrub, 

 even at a considerable distance, by the general form. In 

 many species we recognize great variations in coloring while 

 the form remains fairly constant, so that we speak, for ex- 

 ample, of the red fox and the silver fox. In some species 

 there is great variation as to the size which the individual 

 may attain, although the general shape remains almost uni- 

 form. In some species, as the common dog, there are so 

 many " varieties " that we should be disposed to classify some 

 of the types as totally distinct species. There is more differ- 

 ence, for example, except for our familiarity with the ani- 

 mals, between a mastiff or a greyhound and a Pekinese or a 

 bulldog than we commonly observe among such distinct 

 species as wolf and hyena. Nevertheless, it is a part of 

 our ordinary experience that a living individual, whether 

 plant or animal, has a particular form which is common 

 to all members of the species aTid is thus distinctive of the 

 species. 



This fact of a distinct form is true of all living things, al- 

 though it is not confined to living things, for many of the 

 non-living objects found in nature also have characteristic 

 shapes — for example, crystals of various kinds, volcanoes, 

 river deltas, and so on. Most artificial objects also have dis- 

 tinct forms. 



