A WORLD IN THE WATER 95 



shallows. This is not by any means the case 

 in all instances. The beginner in the study of 

 seaweeds soon finds out that representatives 

 of all the classes may be found growing near 

 to the high tide mark. Some very bright green 

 seaweeds {Struvea) have been found at a depth 

 of more than a hundred feet, where, theoretic- 

 ally, the red and the orange rays must be almost 

 entirely screened away. One must, therefore, 

 be careful not to dogmatise on the question 

 of the habits of the seaweeds. In a general 

 way, however, we may say that in the deeper 

 waters the red seaweeds will preponderate ; in 

 moderate depths we shall find the brown 

 seaweeds most in evidence ; whilst in the 

 shallows the green varieties are most likely to 

 be abundant. 



Although in a rough way one may speak of 

 the leaf, the stalk, and even the root of a sea- 

 weed, it should be remembered that these 

 terms will have only a limited significance. 

 Even in the most distinctive of the seashore 

 species there is nothing to correspond with 

 the parts of the higher land plants. The root- 

 like processes, for instance, are largely a means 

 of attachment to hold the plant in one posi- 



