S YMBIOSIS. 



337 



-— I 



occurs between plants and animals. Various species of plants 

 attach themselves to ani- 

 mals by which they are 

 carried about. The plant 

 is thus aided in obtaining 

 the materials for food, 

 and not infrequently the 

 plant conceals the animal 

 from another which seeks 

 it as prey. In this way 

 certain crabs are hidden 

 by algae attached to them. 

 One of the most striking 

 cases of protective mimicry 

 is that in which an Aus- 

 tralian fish has acquired 

 surface outgrowths which 

 imitate almost precisely the 

 appearance of brown sea- 

 weeds, SO that, when quiet, Fig. 376.— A young clover plant, showing tuber- 

 cles, t, on the roots. Natural size. — After 



it looks like a stone to Goff. 



which seaweeds had attached themselves. Thus it often 



escapes its enemies, as does the crab with its 



mask of real seaweeds. 



B. Helotism. 



462. 1. Fungi and algae. — Helotism 

 exists between fungi and algse, constituting 

 F lchll~^dotl the bodies known as lichens, in which the 



<nvTlfplng ee an g afg 5 l' fun g US is the master and the al S a the slaVe * 



Sr^dia^ (See f 54*, and fig. 377.) The same 



After Kemer. f un g US may be found enslaving more than 



one species of algae even within the same mycelium. The 



protonema of mosses or even the leaves of some small 



