BIOLOGY AND NATURAL HISTORY 247 



and a few species were found equal to lemons in vitamin C content. It is 

 possible also that seaweeds, if pulverized and added to fertilizers, would 

 supply essential trace elements to depleted soils. 



The uses and value of agar from North Carolina seaweeds will prob- 

 ably be increased when further technological data are available. Gracilaria 

 and Hypnea agar should be electrodialyzed to obtain the free agar acid and 

 then neutralized with various bases to obtain a variety of agarinates. The 

 properties of each should be studied and compared with various agars 

 already on the market. 



Study of the carbohydrate portion of North Carolina phycocolloids is 

 needed in order to determine the nature and structural formula of the carbo- 

 hydrate units. Such studies might lead to methods of preparation of synthetic 

 agar, or to methods of altering the properties of Gracilaria and Gelidium 

 agar. 



The unique properties of Hypnea agar suggest other fields of study. 

 Additional data are needed on the remarkable effect of various solutes, 

 both electrolytes and non-electrolytes, on the behavior of Hypnea extrac- 

 tive. The nature of the ash of Hypnea extractive has never been studied, 

 and the amount has been only roughly determined. The slight seasonal 

 variation of Hypnea extractive has just been realized; nothing is known 

 of its nature or significance. 



Further work on the discovery by DeLoach - that agar precipitated with 

 ethyl alcohol can be re-dissolved in cold water, if the precipitate is not 

 permitted to dry, might lead to a special use for this phenomenon. Valuable 

 data in the field of colloidal chemistry and physics might result from a 

 comparative study of the swelling of Gracilaria and Gelidium agar in the 

 presence of various electrolytes and other solutes. 



The necessity of the investigator's preparing his own agar from care- 

 fully selected and identified seaweed for which date and place of collec- 

 tion are known cannot be over-emphasized. Much work on chemistry and 

 physics of agar was done on that from Japan, which was almost always a 

 mixture of extractives from several species of seaweeds. Thus the results 

 are of very limited value and are scarcely capable of duplication. Even 

 American commercial agar producers cannot avoid contaminating sea- 

 weeds that might affect chemical and physical properties of the product. 



In addition to the three species of seaweeds already of economic impor- 

 tance in North Carolina, there are others of potential value. Only prelim- 

 inary studies (unpublished) have been made on the algin from Sargassum 

 often available in quantity in North Carolina. Among red algae known to 

 yield a phycocolloid are Agardhiella tenera, Laurencia tuberculosa, Chondria 



2. Bull. 3, Duke Marine Lab., 1946. 



