6 ANIMAL LIFE AND SOCIAL GROWTH 



one such was pointed out by Charles Darwin 

 long ago. Succinctly stated it is that the more 

 maiden ladies in an English farming community, 

 the more clover seed will be produced per acre. 

 The reasoning is: the more old maids, the more 

 cats; the more cats, the fewer mice; the fewer mea- 

 dow mice, the more bumble bees; clover is polli- 

 nated by bumble bees, hence the more bumble 

 bees, the better the pollination and the more 

 clover seed. 



The balance of life in a community is never 

 complete; always there is change. If a progres- 

 sive chamber of commerce attracts a new factory, 

 the village stream may be dammed and breeding 

 places be made for myriads of mosquitoes; if some 

 of these are the malaria bearing Anopheles, mala- 

 ria may become common and the village will 

 suffer from the resulting chills and fevers. Mean- 

 time the range of fishes, mussels and water in- 

 sects has been expanded; boating and bathing 

 facilities have increased and the whole community 

 is directly or indirectly affected. 



Similarly a mild winter which does not kill off 

 the usual number of insects that feed upon plants 

 may result in such orchard and garden depreda- 

 tions that more than the usual amount of human 

 food will have to be imported. Meantime the 

 insects themselves are furnishing an unusually 



