BIOLOGY AND NATURAL HISTORY 233 



The real economic value of seaweeds in America, however, lies with seaweed 

 extractives, principally agar, algin, and agar-like phycocolloids such as 

 carrageenin from "Irish moss." 



BROWN ALGAE 



The economic value of brown algae is limited to a subgroup known as 

 kelps. The principal product is algin, usually sold as sodium alginate. It is 

 a colloidal carbohydrate that forms very viscous aqueous solutions for which 

 there is a wide variety of uses, particularly in foods. Algin does not have 

 the gel-forming property of agar, hence its uses are somewhat different. 

 Products of secondary importance obtained from kelps include the poly- 

 saccharide, laminarin, and the complex alcohol, mannitol. In addition, dried 

 and pulverized kelps are used in health foods and stock feed as a source of 

 essential trace elements. 



In the past, kelps were widely used as a source of potash and iodine, 

 obtained by burning the seaweed, and of acetone and calcium acetate, 

 obtained by fermentation. Seaweeds are no longer used as raw material for 

 these substances, as less costly sources have been discovered. 



Since kelps are cold water species, the algin industry of the United States 

 is located in New England and in the Pacific coast states of California, 

 Oregon, and Washington. Along the Atlantic coast, kelps do not grow in 

 abundance of commercial value south of Massachusetts. New Jersey is the 

 southern known limit of the kelp group. 



A genus of brown seaweeds that contains algin is Sargassum or "Gulf] 

 weed," that occurs off the coast of North Carolina and southwards. The 

 algin content of Sargassum seems to be somewhat less than that of kelps, 

 and its quality is said to be inferior. For these reasons and because of its 

 irregular occurrence on beaches and thin distribution at sea, commercial 

 collection for algin alone may be too costly. 



The plant is characterized by an abundance of small, spherical, berry- 

 like air bladders distributed along its branches that make it one of the few 

 kinds of seaweeds that float. The species-groups of Sargassum indigenous 

 to the Gulf Stream and Sargasso Sea are rarely found growing attached. 

 Large quantities are washed ashore by east or southeast storms. 



The value of Sargassum as a source of algin, trace elements, and other 

 substances has not been investigated adequately. What appears at present 

 to be an inferior grade of algin may prove to have characteristics of special 

 value. It is conceivable that a North Carolina seaweed factory that uses 

 other seaweeds might process Sargassum whenever sufficient raw material 

 is available. 



