SEAWEEDS 465 



7. Verdigris Agaric (Stropharia ceruginosa). In vigorous specimens the whole 

 fungus is of a bright green colour, but in the open the cap (2-3 inches diameter) 

 bleaches to a pale dingy yellow. Very glutinous. 



Stem Scaly below ring. 

 Gills Becoming purple. 



8. Purple Agaric (Cortinarius purpurascens). Distinguish this species from 

 BLEWITS and AMETHYST AGARIC. In the poisonous species the stem has 

 a bulb at the base, and the gills are rusty -coloured when mature. 



Cap Very glutinous. 



Flesh Rather thick, clear blue. 



[For the above notes I am indebted to the pamphlet mentioned previously, published by the 

 Board of Agriculture and Fisheries.] 



Seaweeds. 



The Seaweeds, the remaining members of the sub-kingdom Thallophyta, 

 are classified according to their colour. 



That portion of the sea which forms the shore-belt has been divided into 

 four zones, in each of which, generally speaking, seaweeds of one of four colours 

 are found living. 



1. At and above high-water mark, they are chiefly thread-like and encrust- 

 ing species, which under the microscope appear bluish green CYANOPHYCE^;. 



2. From high-water mark to a line about half-tide level, they are chiefly 

 of a bright green colour CHLOROPHYCE^E. 



3. From half-tide level to low-tide mark, they are chiefly olive-brown 

 PHJSOPHYCE^E. 



4. From low-tide mark to deep water, they are red RHODOPHYCE.E. 



In all cases the green colour (chlorophyll) commonly associated with 

 land plants is present, but in the olive-brown and red varieties it is masked 

 by these other pigments, which serve to protect it against injurious rays of 

 light. 



The green seaweeds found about high-water mark are able to bear the 

 same amount of light as land plants ; but the brown weeds, from their position 

 between high and low water mark, are exposed twice each day to great changes 

 of light, and therefore need more protection, while the red varieties, growing 

 only in deep water, find their red pigment (like the photographer's red glass 

 window) a special safeguard against the injurious blue rays of light which 

 penetrate to their depth. 



Seaweeds are useful for many purposes, edible, agricultural, and com- 

 mercial. Some species may be made into a jelly, others can be treated as a 

 vegetable dish. Some are used by the farmer as manure upon his land, while 

 the larger and coarser species were formerly used to produce Kelp, an impure 

 carbonate of soda. All marine Algae contain iodine, and some are occasionally 



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