INTRODUCTION 13 



III. Communities and societies. The bond ex- 

 isting between all the constituent parts of a society 

 is not of the same nature as that which unites the 

 members of a colony or the cells of an animal or 

 plant. These physiological bonds are not compar- 



sea, and after living there a certain time, enters the female oepha- 

 lopod, to effect impregnation. 



The individuality of this hectocotyle appears so obvious that 

 for a long time it was regarded as a distinct species some kind 

 of worm. At first sight, then, the hectocotyle seems to be an 

 individual. This, however, is not the case, as it reproduces, not 

 a hectocotyle but a cephalopod. 



Many Echinoderms, by a spontaneous act of protection, can 

 separate their arms from their bodies. Such a separated arm 

 may live, feed and slowly build up again a whole Echinoderm. 

 Plainly, it would be impossible to indicate the precise point at 

 which such an organ should be regarded as an individual. The 

 vegetable kingdom abounds in analogous facts. A strawberry 

 plant, for instance, gives off runners in the course of the Summer, 

 which take root, and themselves become strawberry plants. So 

 long as these young plants are insufficiently developed to main- 

 tain themselves, the mother-plant continues to supply them with 

 nourishment. As soon, however, as the young shoot can dispense 

 with this support, the runner atrophies, and the little plant begins 

 a separate existence. By prematurely cutting the runner, the 

 new plant may be compelled to live alone sooner than it naturally 

 would have done. 



With some other plants (Phalangium viviparum) the young 

 shoots frequently retain their connection with the mother-plant, 

 although quite capable of maintaining themselves. Under these 

 circumstances it is obviously impossible to say if these plants 

 represent colonies or free individuals. Speaking generally, it 

 may be said that no precise line can be drawn between colonies 

 and individuals. Many writers on the subject, and Perrier among 

 the number, consider that every colony where there is a physical 

 continuity among the members, should be regarded as an in- 

 dividual. 



