XXV 



H. 



ORGANS FOR LOCOMOTION AND FLOATING. 

 BORING. FIXATION. 



(Including those of Spores, Seeds, and Fruits.) 



At some period in the life of all organisms they are fitted to 

 change their locality, either by their own spontaneous motion ; 

 by becoming attached to other motile bodies ; or by being 

 carried by currents in air or water. This change of place is 

 necessary in all to prevent overcrowding, and in most for 

 obtaining food, seeking members of the opposite sex, avoiding 

 inimical conditions, or obtaining fresh shelter. 



1. Locomotion on Solids. 



The mechanism of locomotion on solids is the same in water 

 and air, on sewz-solids in water the locomotion is the same as on 

 solids in air ; the animal receiving more support from water, so 

 that it will not sink when moving on submerged mud or sand. 



CREEPING. 



Movement usually slow, with generally a large surface in 

 contact with the ground. Not effected by paired jointed appen- 

 dages, although they may be used for grasping (this character 

 is artificial but convenient). 



By contraction at one part forcing fluid protoplasm to the 

 opposite relaxed side ; this results in a flowing movement from 

 the contracting to the relaxed regions, which are driven forwards 

 as root-like processes (pseudopodia). 



Plants. 



Example. Myxomycetes. 



Animals. 



Example. Rhizopoda. 



