4 3 EDIBLE FRUITS AND SEEDS. [CHAP. 



replied his friend, " I see no difficulty in that, because 

 if it were not for the teeth, how could we distinguish 

 the species ? " 



We may, however, no doubt, safely consider that 

 the peculiarities of seeds have reference to the plant 

 itself, and not to the convenience of botanists. 



In the first place, then, during growth, seeds in 

 many cases require protection. This is especially the 

 case with those of an albuminous character. It is 

 curious that so many of those which are luscious when 

 ripe, as the Peach, Strawberry, Cherry, Apple, &c., 

 are stringy, and almost inedible, till ripe. Moreover, 

 in these cases, the fleshy portion is not the seed itself, 

 but only the envelope, so that even if the sweet part 

 is eaten the seed itself remains uninjured. 



On the other hand, such seeds as the Hazel, Beech, 

 Spanish Chestnut, and innumerable others, are pro- 

 tected by a thick, impervious shell, which is especially 

 developed in many Proteaceae, the Brazil-nut, the so- 

 called Monkey-pot, the Cocoa-nut, and other palms. 



In other cases the envelopes protect the seeds, not 

 only by their thickness and toughness, but also by 

 their bitter taste, as, for instance, in the Walnut. 

 The genus Mucuna, one of the Leguminosae, is remark- 

 able in having the pods covered with stinging hairs. 



In many cases the calyx, which is closed when the 

 flower is in bud, opens when the flower expands, an<i 

 then after the petals have fallen closes again until the 

 seeds are ripe, when it opens for the second time. 

 This is, for instance, the case with the common Herb 

 Robert (Geranium robertianuni). In Atractylis can- 

 cellata, a South European plant, allied to the thistles, 



