66 Gleanings from the 



To fhow the manner in which one part of 

 nature influences and acts upon others until the 

 fauna or flora of a diftrict may be changed by 

 what feem, taken feparately, infignificant caufes, 

 it is worth while quoting a fpeculation of Darwin, 

 in which the cat plays a confpicuous part. " The 

 common red clover is only vifited by humble- 

 bees, as hive-bees cannot reach the nectar. The 

 heartfeafe (viola tricolor) is another plant which 

 alfo feems to owe its fertilization only to humble- 

 bees. It may be regarded, therefore, as highly 

 probable that if the whole genus of humble-bees 

 became extinct or very rare in England, the 

 heartfeafe and red clover would become either 

 very rare, or would altogether difappear. The 

 number of humble-bees in a diftrict depends in a 

 great meafure on the number of field-mice, which 

 deftroy their combs and nefts. It is eftimated that 

 more than two-thirds of them are thus deftroyed 

 all over England. The number of mice is largely 

 dependent upon the number of cats, and it has 

 been found near villages and fmall towns the nefts 

 of humble-bees are more numerous than elfewhere, 

 which is attributed to the number of cats which 

 deftroy the mice. Hence it is quite credible that 

 the prefence of a feline animal in large numbers in 

 a diftrict might determine, through the interven- 

 tion firft of mice and then of bees, the frequency 

 of certain flowers in that diftricl:." 1 



" There remains to be told but one more cat 

 ftory of importance. It claims to be of recent 

 1 See "Origin of Species," ut fup., p. 57. 



