CHAPTER VII. 

 PLANTS AND ANIMALS. 



64. We have no difficulty in distinguishing the cow 

 from the clover she feeds upon; nor the bee from the 

 flower that it visits. They differ much, both in their 

 outward form and in their internal structures. But 

 even these organisms, with all their differences, have 

 mucli in common: they are alive, which is the most im- 

 portant thing that can be said about them; they use 

 food; they grow; they are organized; they are made up 

 of cells and of protoplasm; they reproduce; they die; 

 and when they die they decompose into similar inorganic 

 constituents. 



65. Doubtful Forms and their Meaning. As we con- 

 sider the lowest plants and the lowest animals, micro- 

 scopic forms, it is even more difficult to frame our defi- 

 nition of plants and animals in such a way as to make 

 a satisfactory division. Indeed, there are some forms 

 of organisms which we cannot surely call either plants 

 or animals. 



This would be surprising and disconcerting if we con- 

 sider that the plant and animal kingdoms were created 

 perfect and distinct as we now have them. If, however, 

 they are really kin to each other, and are merely dif- 

 ferent kinds of living things, derived from a common 

 stock by long growth and gradual change, then this 

 condition is exactly what we should expect. The dia- 

 48 



