64 Plant Life and Evolution 



weeds, are far less conspicuous than the great kelps, 

 owing both to their much smaller size, and to their 

 growing, as a rule, in deeper water, or under the 

 shelter of larger seaweeds and rocks, where they are 

 easily overlooked. They include some of the most 

 exquisite of all plants, and their beautiful tints and 

 graceful forms are familiar to every one who has 

 made even a casual study of marine plants. 



The rose-red pigment which quite hides the green 

 chlorophyll in the living plant is easily extracted by 

 fresh water, and then the presence of chlorophyll 

 is plainly seen. This red pigment probably supple- 

 ments the chlorophyll in the process of photosynthe- 

 sis, and enables the chlorophyll bodies to absorb cer- 

 tain light rays which would otherwise be unavail- 

 able owing to the deep water in which they grow. 



A marked peculiarity of the red seaweeds is the 

 complete absence of any motile reproductive cells, 

 such as are so common in the green and brown 

 algae. The result of fertilization is not a single 

 spore which directly or indirectly produces a new 

 plant, but there is formed a multicellular structure, 

 or " spore fruit," which by budding gives rise to 

 many spores. The complete absence of any motile 

 cells in the red algae is difficult to explain, as it is 

 hard to see what advantage this can be to the plant. 



The red algae are not so exclusively marine as 

 the brown seaweeds, and there are a good many 

 species which live in fresh water. These fresh- 

 water forms have, as a rule, but little of the red 



