148 PROTECTION OF THE GREEN TISSUE. 



behind, and last through the winter and even 

 through the following summer. In the niche 

 between these stipules, which make with each 

 other an angle of 120!, nestles the bud, which 

 unfolds in the following spring. As long as the 

 tender young leaves remain in the niche between 

 the thorny stipules (Fig. 40, 4), they are carefully 

 shunned by animals ; and only when they have 

 grown beyond these thorny points, does this pro- 

 tection come to an end. 



Most of these protective contrivances only pro- 

 tect the green leaf while it is in a young state. 

 But it is just at this time that defence is most 

 needful. If single leaves which project beyond 

 the thorns are eaten, a part of the leaves remain, 

 and the loss is not of much importance. 



One extremely curious means of defence is not 

 mentioned in the foregoing article. Certain plants 

 secrete a nectar which is very attractive to black 

 ants, who, therefore, take up their abode upon 

 these plants, and constitute a sort of standing 

 army, ready to resist furiously the onslaughts 

 of leaf-cutting ants, of caterpillars, and even of 

 the larger animals. 



