PIONEER COMMUNITIES 



141 



formation because of their breeding relations. The large-mouthed 

 black bass, the bluegill, the pumpkin-seed, and the speckled bullhead 

 all make nests on the sand, the male fish guarding the nests and driving 

 off other fish that approach. These species are the same as those of the 

 bare-bottom formations of a lake. In their feeding the fish belong in 

 part to another formation in the pond, namely, that of the chara. 



Character of the formation : The formation may be designated as the 

 bare-bottom formation, the forms present being those that are dependent 



FIG. 85. Shows Pond i at the extreme low water of the drought of 1908. In the 

 spring the old boat is usually covered with water. In the foreground a large area of 

 bare sand bottom is shown; to the right a few rushes and sedges. The absence of 

 shrubs near the water's edge should be noted. 



upon bare bottom in their most important activities the fish in breeding, 

 the caddis-worms in making their cases, the mussels in their general 

 activities. It is necessary for the mussels to be on bare bottom in order 

 to maintain themselves in an upright position. 



Tendencies in the formation : This formation is similar to that of the 

 bare bottom of lakes. The vegetation comes in, as has been indicated in 

 the protected situations, and the bare bottom disappears, its place being 

 taken by the chara. The chara gives rise to humus, upon which chara 



