8 THE VICTORIAN NATURALIST. 



entirely wanting in seaweeds. Another marked difference between 

 Alg?e and land plants is found in the absence of true roots, stems, 

 and leaves. The casual observer may object to this statement, 

 as many seaweeds appear to have all three ; but when examined 

 carefully the apparent roots, stems, and leaves will be found to 

 be only masses of cell tissue, without either the structure or 

 function of these organs. 



Structure and form are not the only characters we have to 

 notice. Seaweed derives a good deal of its nourishment from the 

 mineral salts contained in sea water, and these, together with a 

 certain amount of water, are absorbed by the plant ; but a most 

 important ingredient of its food, carbon, can only be obtained by 

 the help of a peculiar green substance termed chlorophyll, which 

 Algge contain in common with most land plants. Under certain 

 circumstances this chlorophyll is masked or hidden by brown, 

 olive, or red pigments, so that we find seaweeds of many colours. 

 Colour is particularly noticed in Alga?, as with it is usually asso- 

 ciated some important characters, such as reproduction, locality, 

 &c. Botanists have therefore divided seaweeds into green (Chlo 

 rophycese), brown or olive (Phaeophycese), and red (Rhodophyceae). 

 With reference to their methods of reproduction, it will be more 

 convenient to explain them in connection with a few special 

 plants as occasion requires. 



On visiting the seashore it may be that the tide is in, so that 

 we can only stroll along the edge of the water, and pick up an 

 occasional seaweed drifted in and thrown on the shore by the 

 waves. We ought to place these by themselves, as we cannot be 

 certain of their locality. 



After a time the tide begins to recede, and our first rocky pool 

 is accessible. Going down on our knees, knife in hand, we slip 

 the blade under a delicate structure as close to the rock as 

 possible, then place our first find in our bottle. 



A common salt-jar filled with seawater will be found very useful 

 for this purpose. If we notice the contents of this pool carefully we 

 shall first observe that most of the seaweeds are of a bright green 

 colour. As the blue Alg?e (Cyanophycege) are for the most part 

 too small to be easily seen, we may pass them over with the 

 remark that they are either unicellular or form chains of cells, 

 either naked or surrounded by a gelatinous covering. Amongst 

 the mass of vegetation in the pool we get confused, and hardly 

 know where to begin. Tufts of delicate green hair-like plants 

 waving backwards and forwards with the motion of the tide catch 

 our eye ; at the first glance they all appear alike, but soon we can 

 distinguish that some are elongated threads that do not branch ; 

 these are Confervse. The beautiful branched ones are Clado- 

 phora. They are closely allied, and both are formed of cell fila- 

 ments. From any of the cells of Cladophora gametes may be 



