THE BROWN ALGAE-ALGIN FROM KELPS AND FUCOIDS 97 



Harvesting kelp in this manner has caused the kelp beds to become more 

 abundant as controlled kelp-cutting stimulates growth and reduces destruction 

 by disease and storms. If kelp is permitted to mature it eventually sloughs off and 

 washes up on beaches in large quantities. Also, older kelp is less resistant to 

 bacteria and parasites. 



Several mechanical methods for the harvesting of Laminaria are being studied 

 at the Institute for Seaweed Research at Musselburgh, Scotland; some have 



(Courtesy U. S. Fish and IVildlife Service) 

 Fig. 6-1. Fronds of the giant kelp {Macrocystis pyrifera) float on the surface of the 

 water supported by the gas nodules at the base of each leaf. This plant is one of the 

 several algin sources. 



already been developed. A specially designed grapnel, which is lowered to the 

 bottom, then raised and emptied, has proved satisfactory. A conveyor arrange- 

 ment with hooks at each link permits a constant flow of seaweed to the boat. 

 Further development of this apparatus is in progress. Another method involves 

 a large, flexible tube with a rotating cutter at one end. The cutting end is 

 dragged along the bottom and the cut seaweed drawn up through the tube 

 with a stream of water by means of a pump. A trawl with cutting blades, or 

 wires, and a rigid wire and metal collecting frame is also being tested. 



Processes of Manufacturing Algin and Alginates 



Stanford's Process. The process used by Stanford in his factory in Scotland 

 during the latter part of the 19th century may be briefly described as follows: 

 Drif tweed (consisting chiefly of Laminaria digitata and Laminaria stenophylla) 

 was macerated (heated or unheated) for 24 hours with one-tenth of its weight of 

 sodium carbonate. The plants completely disintegrated, resulting in an extremely 

 viscous, semigelatinous mass which was difficult to filter. It was necessary to 

 gently heat a cold solution to enable it to filter through coarse filter bags; cellulose, 

 sand, etc. were retained. Addition of either sulfuric or hydrochloric acid pre- 



