IODINE AND OTHER CHEMICALS 61 



Algae are relatively simple plants, commonly 

 called seaweeds, which ordinarily grow either under 

 or partly under water. They differ from land plants 

 in that they lack true differentiation into root, stem, 

 and leaf; reproduction takes place by means of 

 spores. Algae, however, resemble the plants with 

 which we are familiar in that they are able to synthe- 

 size carbohydrates, such as sugars and pectins, from 

 carbon dioxide and water by means of the energy 

 which they receive from the sun's light rays. The 

 blue-green and green algae live only in shallow 

 water at depths where they receive blue light. Red 

 algae are found at much greater depths where only 

 the red rays penetrate. Brown algae are found at the 

 intermediate depths. 



The algae burned in the preparation of iodine are 

 green or brown in color, usually fuci or laminaria, 

 which grow in relatively shallow water. Three species 

 of laminaria are commonly burned in Europe for the 

 production of iodine; their common names are sea- 

 girdles or tangle, bulbous-rooted tangle, and sweet 

 tangle. Four fuci also are commonly collected, which 

 are known to the kelp-burners as black wrack, yel- 

 low wrack, bladder fucus, and siliquosa. Other 

 species of algae are also used; in fact, almost any 

 seaweed found on the beach may be utilized in this 

 way. 



Harvesting of Seaweeds 



Since the seaweeds are widely scattered along the 

 shores, they are cut by hand by the poorer classes 

 of people living in the neighborhood of the beds. 



