126 COLIN CLOUT'S CALENDAR. 



whitehearts you will see how well it is fitted to perform 

 the functions for which the tree has produced it. It has 

 a bright outer coat, to attract the eyes of birds, and 

 especially of southern birds for England is near its 

 northern limit, and it is a big fruit for our native species 

 to eat ; rowan-berries, haws, and bird-cherries are rather 

 their special food in our. northern latitudes. Then, 

 again, it has a sweet pulp to tempt their appetite : sweet- 

 ness and bright colour in plants being almost always 

 directly traceable to animal selection. But inside, its 

 actual seed is protected by a stony shell ; while its 

 kernel is stored with rich food-stuffs for the young seed- 

 ling, laid by in its thick seed leaves, which form the 

 .two lobes of the almond-like embryo. The flower, it is 

 true, has a pair of separate ovules, which ought, under 

 ordinary circumstances, to develop into two seeds ; but 

 as the fruit ripens one of them almost always atrophies. 

 Such diminution in the number of seeds invariably ac- 

 companies every advance in specialisation, or every fresh 

 forward step in. appliances for more certain distribution. 

 The little hard nuts on the outside of the strawberry 

 number fifty or sixty ; the nutlets of the raspberry num- 

 ber only some twenty or thirty ; the pips of the apple, 

 relatively ill protected by the leathery core, range from 

 five to ten ; the stones of the haw, with their bonier 

 covering, are only two : but in the plum tribe, with their 

 extreme adaptation to animal dispersion, the seeds have 

 reached the minimum irreducibile of one. 



It is this highest tribe of all, accordingly, that supplies 

 us with what we call distinctively our stone-fruits. The 

 sloes of the common blackthorn have grown under cul- 

 tivation into our domestic plums ; the two wild cherries 



