i8 THE EVOLUTIONIST AT LARGE. 



but when the seed begins to set the potcntilla 

 develops only a collection of dry fruitlets, 

 seated upon a green receptacle, the bed or 

 soft expansion which hangs on to the ' hull ' 

 or calyx. Each fruitlet consists of a thin 

 covering, enclosing a solitary seed. You may 

 compare one of them separately to a plum, 

 with its single kernel, only that in the plum 

 the covering is thick and juicy, while in the 

 potentilla and the fruitlets of the strawberry 

 it is thin and dry. An almond comes still 

 nearer to the mark. Now the potentilla 

 shows us, as it were, the primitive form of 

 the strawberry. But in the developed ripe 

 strawberry as we now find it the fruitlets are 

 not crowded upon a green receptacle. After 

 flowering, the strawberry receptacle lengthens 

 and broadens, so as to form a roundish mass 

 of succulent pulp ; and as the fruitlets ap- 

 proach maturity this sour green pulp becomes 

 soft, sweet, and red. The little seed-like 

 fruits, which are the important organs, stand 

 out upon its surface like mere specks ; while 



