How Plants Secure Change of Location 395 



agencies of nature, so far as utilization by plants is concerned, 

 are animals, which forever are roaming among plants in their 

 search for food or for shelter. And in general where plants are 

 most plenty, there animals too most abound. There is, by the 

 way, a kind of poetical justice in plants 

 making animals do service for them as 

 some return for the priceless benefits they 

 confer upon animals. 



The ways in which animals are made 

 to cooperate in the dissemination of 

 plants are various. In the first place, as 

 in case of other methods, some transport 

 is incidental, that is, it occurs without FlG 1G6 ._ The hooked fruits 

 the existence of any particular adaptations of Burdock - 



thereto. Thus the seeds of some water plants are carried vast dis- 

 tances embedded in the mud which adheres to the feet of the larger 

 and wide-ranging water birds, some of which have been shot with 

 such seeds attached to their feet or their feathers. Again, some 

 heavier seeds, such as nuts, are carried away by squirrels or birds 

 to be eaten elsewhere or stored up for winter; but some are dropped 

 on the way and others never are used, so that they come to grow 

 in new places. Probably also the scattering of spores of Mildew, 

 or other leaf Fungi, by temporary adhesion to the slimy bodies of 

 snails is of similar nature. 



Turning now to the definite adaptations which fit seeds for 

 transport by animals, we find first of all a simple and obvious 

 method in the provision of hooks or other arrangements suitable 

 for attachment of seeds to fur or to feathers. Everybody will 

 recall the case of the close-clinging Burdock (figure 166), while the 

 Cocklebur and the Agrimony are equally efficient. Some striking 

 examples occur in the plants of great plains, where large animals 

 are especially abundant, as for instance the Unicorn Plant of the 

 west (figure 167) which catches in the tails of horses, and the 

 Grappling plant of South Africa (figure 168), which entangles 



