Fruits and Seeds. 171 



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. 



4. On the other hand, such seeds as the Hazel, 

 Beech, Spanish Chestnut, and innumerable others 

 are protected by a thick, impervious shell, which is 

 especially developed in the Brazil-nut, the so-called 

 Monkey Pot, the Cocoa-nut, and other plants. 



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. 

 One genus (Mucund) is remarkable in having the 

 pods covered with stinging hairs. 



5. In many cases the calyx, which is closed when 

 the flower is in bud, opens when the flower ex- 

 pands ; and 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 (fig. 68). In a South 

 European plant allied to the thistles the outer 

 envelopes form an exquisite little cage. Another 

 case, perhaps, is that of Nigella, or, as it is seme- 

 times more prettily called, " Love-in-a-Mist," of 

 old English gardens. 



6. Again, the protection of the seed is in many 

 cases attained by curious movements of the plant 

 itself. In fact, plants move much more than is 

 generally supposed. So far from being motionless, 



