How Plants Secure Change of Location 379 



advantageous in the struggle for existence. And other reasons 

 exist, of lesser weight, which combine with those given to explain 

 both the need and the value of a change of location. 



The methods whereby plants secure this change of location are 

 many and various, but fall somewhat naturally under these 

 divisions : — 



1. Independent Locomotion 



2. Extension through Growth 



3. Projection by Elastic Machinery 



4. Waftage by Winds 



5. Flotage upon Water 



6. Carriage by Animals 



The roll of these methods will recall to the reader our dis- 

 cussion of the use of the very same ones in connection with cross 

 pollination. They are, in fact, substantially the same, as would be 

 inferred from the similarity of the problems presented to the 

 plant in the two cases. The chief differences are connected with 

 the greater difficulties of cross polhnation (for here a definite 

 goal as well as a definite starting place is imposed), and with the 

 extreme fineness and hghtness of pollen, which makes its pro- 

 pulsion from plant to plant impracticable. But the identity of 

 method in the two processes should not be permitted to create 

 any confusion between them in the mind of the reader, who 

 should keep very clearly in mind the totally different object in 

 the two cases. 



1. Independent Locomotion. — Although none of the higher, or 

 familiar, plants possess this power, it is well developed in the sim- 

 pler kinds which lack the firm cellulose skeleton; and the method 

 thereof is precisely the same as is used by the simpler animals. 

 Thus, some kinds creep, as in the case of the Shme-molds (or 

 Myxomycetes), with which the reader has already made acquaint- 

 ance in the chapter on Protoplasm; these opaque-white gelatinous 

 masses are sometimes seen in damp places, — on decaying wood, 

 wet earth, or neglected flower pots, — where they creep about, 



