SOCIAL OR GREGARIOUS ANIMALS. 187 



congregation of the same species in certain 

 localities, wherein multiplication goes on 

 because those localities are favourable. Such 

 animals are congregating, not gregarious ; they do 

 not know each other as every rook knows its 

 fellow, every partridge the members of its own 

 covey ; they merely multiply and live together, 

 but do not associate — nay, they are often at war 

 with each other, the larger preying on the 

 smaller. It strikes us that in this light we 

 must look at the leeches of the quagmire, the 

 worms of the garden mould or of the fields, at 

 the beds of cockles, mussels, and oysters on our 

 coast, at the dancing maze of gnats floating in 

 the air, and at the fishes which live in shoals in 

 the water. The same observation applies to 

 birds which migrate in vast flocks collected for 

 one common purpose from many districts. 

 Humboldt terms many plants social, such as 

 the Fucits natans, which covers leagues of ocean 

 — the heaths, which in dense array spread over 

 our hilly moors — the duckweed (Lemna) of the 

 sluggish stream — the pine of the northern 

 forest ; but in these cases we contend, first, 

 that social is not a proper term, and next, that 

 the peculiarity of soil, w r ater, climate, inducing 

 their multiplication, prevents the intrusion of 

 other plants, that very multiplication tending 

 in its turn to repel their intrusion. Plants, 

 therefore, are not social nor gregarious — con- 

 gregating they may be, only because they find 

 a congenial spot for development. Beings 

 which are gregarious seek each other out, 



