80 THE NATURE AND WORK OF PLANTS 



this plant have traps large enough to receive young 

 fishes, and they kill large numbers of these animals 

 in the course of a season. 



98. Food-building in the lower forms. — The leaf 

 is the most perfect organ for the display of chlo- 

 rophyl in such manner as to make the best use of 

 light, but in lower forms it is done in a simpler man- 

 ner. One generation of the mosses, ferns, and some 

 liverworts are furnished with organs like the leaves 

 of seed plants. In the other generation the body 

 is in the form of a thin plate, or solid mass of 

 cells, which lies flat on the surface of the ground. 

 The chlorophyl in such cases is carried in the upper 

 layers, where it may receive light. The seaweeds 

 exhibit a great variety of organs for this purpose. 

 Some of them are leaflike in general form, while 

 others are massive and carry chlorophyl in the 

 outer layers only; these plants also carry red and 

 blue coloring matter. The pond-scums, which float 

 on fresh water, consist of a chain of cylindrical 

 cells, and the green color is arranged in spiral bands, 

 like corkscrews, which run around just inside the 

 cell wall in all cells except the spores. In still 

 simpler forms the chlorophyl is diffused through 



