CO- OPERA TION. 1 6 1 



as the army, navy, and fortifications are to a^ great 

 nation. Its roots and leaves are the trading or 

 wealth -accumulating members, its flowers are its 

 expending members, its fruits the emigrating part of 

 the population, its thorns and spines leaf- units set 

 apart, as we do our soldiers, for the defence of the 

 general community. 



Weak animals find security in associating to- 

 gether, and mankind have doubtless had their own 

 social character evolved, with all the qualities and 

 attributes belonging to it, from adopting a similar 

 habit. Herbivorous animals collect in herds, birds 

 in flocks, and even insects often in dense crowds. 

 The law which has produced such a tendency 

 has operated in a similar manner among certain 

 kinds of vegetation. Everybody has noticed how 

 the Alpine Gentians, Anemones, etc., have congre- 

 gated in brilliant patches in Switzerland, to the 

 general exclusion of other plants. The Daisies and 

 Buttercups of our English meadows, and the Poppies 

 of our cornfields, flourish best when congregated in 

 numbers. 



A real and most important reason for such a 

 social habit, is probably to tempt insects to their 

 neighbourhood by exhibiting great masses of colour. 

 Many of the " social plants," as Humboldt long ago 

 termed them, have got possession of the ground 

 through being specialised to extreme physical con- 

 ditions, as the Arctic and Alpine flora are to cold, 



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