150 THE BEAUTIES OF NATURE chap. 



for which they would perform no service in 

 return. In many cases, therefore, the open- 

 ing of the flower is either contracted to a 

 narrow passage, or is itself protected by a 

 fringe of hairs. In others the peduncle, or 

 the stalk of the plant, is protected by a hedge, 

 or chevaux de frise, of hairs. 



In this connection I might allude to the 

 many plants which are more or less viscid. 

 This also is in most cases a provision to pre- 

 clude creeping insects from access to the 

 flowers. 



There are various other kinds of hairs to 

 which I might refer — glandular hairs, secre- 

 tive hairs, absorbing hairs, etc. It is marvel- 

 lous how beautifully the form and structure 

 of leaves is adapted to the habits and require- 

 ments of the plants, but I must not enlarge 

 further on this interesting subject. 



The time indeed will no doubt come when 

 we shall be able to explain every difference of 

 form and structure, almost infinite as these 

 differences are. 



