218 BIOLOGY 



tions between the two kingdoms. Indeed, when we analyze 

 the subject to its limit, we find it impossible to draw any sharp 

 line separating animals and plants, for there are some living 

 things which show so few characteristics of either kingdom 

 that we cannot determine with accuracy whether they belong 

 to one group or the other. It is possible, however, to draw a 

 general distinction between the two, and from this general 

 distinction we can derive certain other secondary differences, 

 which are more evident. 



The Fundamental Distinction. The primary distinction be- 

 tween animals and plants is in the process of photosynthesis. 

 The plant kingdom alone has the power of utilizing the rays 

 of the sun and manufacturing starch out of carbon dioxid and 

 water: animals never have this power. From this primary 

 distinction arise several other minor points of difference, more 

 or less sharply separating these two groups. 



Secondary Differences. A . Color. Plants which have the 

 power of photosynthesis are provided with the green coloring 

 matter, chlorophyll. Animals, on the other hand, are not pro- 

 vided with this coloring matter. 



B. Motion. Since animals live upon solid foods, they have 

 to search for it, and they are, as a rule, provided with motion. 

 Plants, on the other hand, having no need to search for their 

 food, since they find it in the atmosphere and soil, have not, 

 as a rule, developed the power of motion. 



The various methods of motion developed by animals may 

 be summarized as follows: (1) Amoeboid movement, as found 

 in Amoeba, by means of lobes of the living protoplasm. It is 

 confined to unicellular organisms. (2) Ciliated and flagellated 

 motion, produced by vibratile, hairlike processes of the proto- 

 plasm. Cilia are moderately short processes, and where found 

 are usually present in large numbers. They are found in 

 many unicellular animals and also in multicellular forms. 

 Even the highest animals have cilia on the cells lining the air 

 passages and various other ducts. Flagella are longer than 



