FEUITS. 93 



Many of the peculiarities just referred to find their expla- 

 nation in physiological adaptations, chiefly those connected 

 with protection and the dissemination of seeds, physiological 

 Attention has already been directed to these in adaptations, 

 our study of seeds, but they may now be briefly noticed 

 with more direct reference to the fruit. Fleshy fruits, par- 

 ticularly if brightly colored, are attractive to animals, and 

 are carried away by them in great numbers, often to very 

 remote places. One has only to recall the habits of birds 

 in distributing seeds of cherries, strawberries, and many 

 other fruits, to realize the importance of these common and 

 familiar but nicely adjusted relations. Other fruits, such 

 as nuts of various kinds, though less attractive externally, 

 are carried away by squirrels and other animals for the 

 sake of the abundant food stored up in them. Still other 

 fruits, such as the samara of the hop-tree and maple, have 

 the pericarp greatly modified in adaptation to dissemina- 

 tion by the wind, and a considerable number of dehiscent 

 fruits exhibit mechanical arrangements by which their 

 seeds are forcibly thrown to a considerable distance. Fre- 

 quently, too, the structure of the fruit is manifestly 

 adapted to secure the protection of the seed. The thick 

 and bitter outer covering of the walnut and its extremely 

 hard shell, the rind of the orange with its pungent, 

 aromatic oil, the extraordinarily multiplied and thickened 

 coverings of the cocoanut, and other arrangements of simi- 

 lar character, are so many means of protection against 

 attacks of animals, the penetration of water and fungous 

 germs, and injury from other destructive agents. 



In systematic botany it becomes necessary, for 'the sake 

 of intelligible description, to employ some one of the 

 various classifications of fruits. At the same time, it must 

 be understood that such classifications are more or less 



