68 IP 6 t e I 5 i a 



at slight elevation above the lake level. 



b. INIid beach. 

 Within this zonal region of the beach, the 

 lakeward and shoreward influences meet and 

 commingle in such a way as to call forth the 

 greatest complexity of conditions. As the forest 

 is a])proaclied the influences of the lake decrease, 

 and in like manner as the \\ater is neared so 

 those of the forest become of less weight. The 

 optimum is therefore established somewhere in 

 the middle zone. Besides the transitions in the 

 societies undergone in ])assing from the front 

 towards the back, one also notes changes in the 

 longitudinal direction of the strand like those of 

 the front beach in passing from low and mucky, 

 to raised sandy beach and stream delta. This 

 longitudinal transition results in the division of 

 the midstrand vegetation into societies more or 

 less distinct and conditioned by the soil com- 

 position. The sandy beaches show a greater 

 variety of species than the low humus ones, but 

 fewer individuals in a given area. This is 

 largely due to the fact that there are more typ- 

 ical turf builders, sedges and the like, found 



