THE ANIMAL IN THE WORLD 533 



plants, even including those like the fungi which have no 

 chlorophyll, cellulose is almost invariably present ; among 

 animals it is unknown. It happens, indeed, that this com- 

 paratively unimportant character comes nearer than any 

 other to giving an absolute distinction between the two 

 kinds of organisms. 



To sum up : we find between typical plants and typical 

 animals the following distinctions : — 



r. The presence in typical plants and not in animals of 

 the green substance chlorophyll. 



2. That while plants absorb through their surface 

 simple inorganic compounds and from them manufacture 

 foodstuffs for their protoplasm, animals swallow the complex 

 substances of the bodies of plants and of other animals. 



3. That while in plants motion is restricted or absent, 

 it is conspicuous in animals. 



4. That plants have a skeleton of cellulose, which is 

 absent from the bodies of animals. 



It will be seen that the differences between ordinary 

 plants and animals are wide and striking. 



?nte?mldilte But the fact must not be overlooked that 

 between intermediate organisms are known. These are 



plants. 8 and not such creatures as the sea anemones, which 

 are true animals with the habit of remaining fixed 

 in one spot, or the fungi, which are probably true plants that 

 have lost their chlorophyll and consequently modified their 

 mode of nutrition, so that they require somewhat more 

 complex food materials. The real intermediate organisms 

 are small creatures related to the Protozoa, which have 

 the power of locomotion like animals, but possess like 

 plants either chlorophyll or cellulose or both. Some of 

 them can hardly be distinguished from the Flagellata. Their 

 existence is a reminder that, fundamentally, all living beings 

 belong to the same stock. In this connection must be 

 mentioned the Bacteria, which are minute, rod-like or 

 spherical organisms often classified with the plants, but of 

 which it is probably more true to say that they are neither 

 plants nor animals, but a third kind of living beings. 



Euglena viridis, often so common in puddles as to give them a 

 green colour, is an example of an organism intermediate between animals 

 and plants. It is a minute, spindle-shaped creature, which may reach 



35 



