THE WONDERS OF LIFE 



ties or individual life-centres," and the unified life of 

 the whole man is the combined result of the work of his 

 component cells. In this way the cells are the real life- 

 unities of the organism. Their individual independence 

 is at once seen in the permanently unicellular protists, 

 of which several thousand species are already known 

 to us. 



On the other hand, we find among the lower animals 

 and the higher plants a composition of homogeneous 

 parts, which represents a higher stage of life-unity. 

 The tree is an individual, but it is made up of a number 

 of branches or individual sprouts, each of which consists 

 in like manner of an axial stem with leaves attached. 

 If we detach such a branch and plant it in the ground, 

 it takes root and grows into an independent plant. So 

 the coral-stem is made up of a number of individual 

 animals or persons, each of which has its own stomach 

 and mouth with a crown of tentacles. Each several 

 coral-individual is equivalent to a single living polyp 

 (actinia). Thus the stem (_cormus) is a higher unity, 

 both in the animal and the plant world. Even the herds 

 of gregarious animals, the swarms of bees and ants, and 

 the communities of human beings, are similar unities; 

 with the difference that the individual persons or citizens 

 are not physically connected, but held together by com- 

 mon interests. We can, therefore, distinguish three 

 stages of organic individuality, one building upon the 

 other — the cell, the person (or sprout), and the stem or 

 state (cormus). Each higher unity represents an inti- 

 mate union of lower individuals. Morphologically, in 

 relation to their anatomic structure, the latter are in- 

 dependent; but physiologically, in respect of the life- 

 unity of the whole, they are subordinated to the former. 



This relation is quite clear in the familiar examples I 

 have quoted.- But there are other organisms in which 

 this is not so, and where the question of the real individ- 



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