BY THE SEASIDE— PLANT LIFE 



Wrack, greenish brown in colour and often as much 

 as six feet in length. It is so named because from 

 the sides of its fiat, leathery, strap-like fronds, there 

 arise little stalked bladders. Right at, and often 

 beyond, low tide mark there dwells the Notched 

 Wrack; very similar to, though larger than, the 

 Flat Wrack, from which it may easily be distin- 

 guished by the fact that the edges of its fronds are 

 toothed, after the manner of a saw. 



It is obvious that the structure of any one of 

 these Wracks is much more complicated than is the 

 case with Ectocarpus. The latter Alga was com- 

 posed of a number of cells, similar to one another 

 in every respect except size. If we tease a stem 

 or a frond of one of the Wracks upon a slide and 

 examine the result of our efforts under the micro- 

 scope we shall see that the cells which compose the 

 Wrack are not by any means similar to one another. 

 Those of us who have mastered the, by no means 

 difficult, art of section cutting, should cut sections 

 of stem and frond and compare them with sections 

 of leaf and stem of some higher plant. The com- 

 parison will show us that, although the seaweed 

 does not exhibit the complicated structure of a 

 flowering plant, it has at least three kinds of dif- 

 ferent cells — an outer layer, a central structure and 

 an intermediate layer. 



If we secure a specimen of the Channelled Wrack, 

 at the end of the summer, we shall notice that the 

 tips of certain of the fronds are swollen. Examina- 

 tion of these swellings under a low magnification 



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