HYDROPHYTE SOCIETIES. 189 



of water is approximately the same. Not only are the 

 plants different in the sphagnum-moor, but they are not so 

 numerous, and, with the exception of the moss, do not 

 grow so densely. It is to be noticed that creeping plants 

 are abundant, and also many forms which are known to 

 obtain their food material already manufactured, and there- 

 fore are saprophytes. Certain kinds of sedges and grasses 

 are found, but generally not those of the swamp-moor, 

 while heaths and orchids are especially abundant. It is in 

 these sphagnum-moors, also, that the curious forms of car- 

 nivorous plants are developed, among which the pitcher 

 plants, droseras, and dionaeas have been described. In 

 considering this strange collection of forms, it is evident 

 that there must be some peculiarity in the food supply, for 

 the heaths and orchids are notorious for their partial sap- 

 rophytic habits, and the carnivorous plants are so named 

 because they capture insects to supplement their food sup- 

 ply. The fact, also, that -the peculiar sphagnum mosses, 

 rather than the mosses of the swamp-moor, are the prevalent 

 ones, indicates the same thing. 



It has been discovered that the water of the sphagnum- 

 moor is very poor in the food materials which are abundant 

 in the water of the swamp-moor. There is a special lack 

 of the materials which are used in the manufacture of pro- 

 teids, and hence this process is seriously interfered with. 

 It is necessary, therefore, to obtain proteids already formed 

 in animals, or in other plants. This will account for the 

 necessity of the saprophytic habit, and of the carnivorous 

 habit, and for the sphagnum mosses which can endure such 

 conditions. Of course, it also accounts for the exclusion 

 of the characteristic plants of the swamp-moor. 



Another peculiarity in connection with the sphagnum- 

 moor, aside from its poverty in food material, is the lack 

 of those low plant forms (bacteria) which induce decay. 

 Bacteria are very minute plants, some of which are active 

 agents in processes of decay, and when these are absent 



