A WAYSIDE BERRY. 21 



indigestible : because, on the one hand, all 

 sour or hard berries would stand a poorer 

 chance of getting dispersed in good situations 

 for their growth, while, on the other hand, all 

 soft-shelled fruitlets would be ground up and 

 digested by the bird, and thus effectually pre- 

 vented from ever growing into future plants. 

 Just in like manner, many tropical nuts have 

 extravagantly hard shells, as only those sur- 

 vive which can successfully defy the teeth 

 and hands of the clever and persistent 

 monkey. 



This accounts for the strawberry being 

 sweet and pulpy, but not for its being red. 

 Here, however, a similar reason comes into 

 play. All ripening fruits and opening flowers 

 have a natural tendency to grow bright red, 

 or purple, or blue, though in many of them 

 the tendency is repressed by the dangers 

 attending brilliant displays of colour. This 

 natural habit depends upon the oxidation of 

 their tissues, and is exactly analogous to the 

 assumption of autumn tints by leaves. If a 



