ECOLOGICAL RELATIONS OF THE FLORA. 37 



5. Thicket and Wooded Sivamp and 



6. Drained Situations. 

 Sand Beach. 



1. Open Beach through drying and Nnnd action becomes 



2. Emhrionic Dune or Upper Beach and this through sand binders 



becomes 



3. Established Dune. Through heaths, shrubs and trees this 



becomes 



4. Dry Ridge and 



5. Jack Pine Barrens. Humus formation and cessation of fires 



change this into 



6. Mixed Pine Woods, which through humus formation become 



7. Mesophytic Woods. 



Sand Point was chosen by Dr. Ruthven as a base largely because 

 of the comparative simplicity of its ph\'siographic features. It is a 

 recent geological formation showing all stages of development even to 

 the very newest. The advantages of such a region to the plant ecologist 

 lie in the fact that the genetics of the plant formations in a region 

 physiographic ally young are more evident than in an older area. The 

 progression is faster, being necessarily^ so in a region that is moving 

 toward the forest formation, for trees are longer in growing and in 

 taking possession of a habitat than sedges, and are correspondingly 

 persistent. 



ECOLOGICAL RELATIONS. 



Hydrophytes — Fresh Water Formations. 



Tm-tle Bay, on the south side of Sand Point, presented quiet water 

 conditions and the resultant hydrophytes (Plate VII b and XIII b). It 

 was a protected arm of Wild Fowl Bay and was very large and shallow, 

 the water varying in depth from six inches to four feet. The muck 

 was about two inches deep; the bottom being frequently exposed in 

 places cleared by the sunfish for their nests. This muck consisted 

 of finely divided silt and water logged vegetal debris. It was seldom 

 compact and in walking on it the foot would sink through this upper 

 layer to the packed sand beneath. 



On the bottom, forming a carpet, the Chara was very strongly de- 

 veloped. This association, however, was not restricted to any given 

 depth in this bay. In this carpet mass was entangled shells, blackened 

 wood, and a large mass of larval cases of the May-fly. The water- 

 lily (Nymphaea advena) and the Chara association were the only marked 

 societies represented, except for a few plants of Potamogcton — (hetero- 

 phyllus, perfoliatus, and pectinatus). The depth of the water seemed 



