THE WEB OP LIFE 53 



flower. I have also found that the visits of bees 

 are necessary for the fertilisation of some kinds 

 of clover — thus, 100 heads of red clover {Tri- 

 folium pratense) produced 27,000 seeds, but the 

 same number of protected heads produced not a 

 single seed. Humble-bees alone visit red clover, 

 as other bees cannot reach the nectar. . . . Hence 

 we may infer as highly probable that, if the whole 

 genus of humble-bees became extinct or very 

 rare in England, the heart's-ease and red clover 

 would become very rare, or wholly disappear." 

 We know that the red clover imported to New 

 Zealand did not bear fertile seeds until humble- 

 bees were also imported. " The number of humble- 

 bees in any district depends in a great measure 

 on the number of field-mice, which destroy their 

 combs and nests ; and Colonel Newman, who has 

 long attended to the' habits of humble-bees, 

 beUeves that more than two-thirds of them are 

 thus destroyed all over England." Now the 

 number of mice is largely dependent, as every 

 one knows, on the number of cats ; and Colonel 

 Newman says ^ " Near villages and small towns 

 I have found the nests of humble-bees more numer- 

 ous than elsewhere, which I attribute to the 

 number of cats that destroy the mice." Thus we 

 may say, with Darwin, that next year's crop of 

 purple clover is influenced by the number of 

 humble-bees in the district, which varies with 

 the number of field-mice ; that is to say, with the 

 abundance of cats ! 



Scattering op Seeds. — It is a fascinating 

 chapter of natural history which tells us how 

 cross-pollination is effected — here by a bee and 

 there by a butterfly, occasionally by a long-billed 



