46 ON THE WINGS OF THE WIND. 



may often find seeds of this type sticking on thorns as 

 the nucleus of a little matted mass of wool, so left by the 

 sheep in the very spots best adapted for the free growth 

 of their vigorous seedlings. 



Even among plants which trust to the involuntary 

 services of animals in dispersing their seeds, a great 

 many varieties of detail may be observed on close inspec- 

 *on. For example, in hound's-tongue and goose-grass, 

 two of the best-known instances among our common 

 English weeds, each little nut is covered with many 

 small hooks, which make it catch on firmly by several 

 points of attachment to passing animals. These are the 

 kinds we human beings of either sex oftenest find cling- 

 ing to our skirts or trousers after a walk in a rabbit- 

 warren. But in herb-bennet and avens each nut has a 

 single long awn, crooked near the middle with a very 

 peculiar S-shaped joint, which effectually catches on to 

 the wool or hair, but drops at the elbow after a short 

 period of withering. Sometimes, too, the whole fruit 

 is provided with prehensile hooks, while sometimes it is 

 rather the individual seeds themselves that are so 

 accommodated. Oddest of all is the plan followed by 

 the common burdock. Here, an involucre or common 

 cup-shaped receptacle of hooked bracts surrounds an 

 entire head of purple tubular flowers, and each of these 

 flowers produces in time a distinct fruit ; but the hooked 

 involucre contains the whole compound mass, and, being 

 pulled off bodily by a stray sheep or dog, effects the 

 transference of the composite lot at once to some fitting 

 place for their germination. 



Those plants, on the other hand, which depend rather, 



