THE CONQUEST OF THE DRY LAND 197 



possible seed or ovule becomes a real seed, which 

 will grow into a plant when it is sown. So the 

 more humble-bees, the better next year's clover 

 crop. 



But the nests of the humble-bees, which are 

 hidden in the ground or in a mossy bank, are 

 often burglared by the field-mice or voles, which 

 devour the white grubs of the bees. So the 

 more field-mice, the fewer humble-bees. 



But the cats on the prowl kill the field-mice, 

 which are therefore scarcer near villages than 

 in the open country. The cats do not appear 

 to eat the field-mice, but they kill them for 

 sport. So the more cats, the fewer field- 

 mice. 



One may perhaps go a step further and say ! 

 The more kindly ladies in the village, the more 

 cats there will be ; and the more cats, the fewer 

 field-mice ; and the fewer field-mice, the more 

 humble-bees ; and the more humble-bees, the 

 better next year's clover crop. 



In any case, we must understand that the 

 pollination or fertilisation of flowers by their 

 insect-visitors, a linkage established after the 

 second great invasion, is one of the most 

 important linkages in the web of life. For the 

 fertilising dust or pollen is necessary if the 



