SWELLING OF MARINE ALGAE 15 



in fresh riiDiiing water for twenty-four hours to remove sea salts 

 and then dried between filter papers. Trios of sections of these 

 dried laminae were swelled in i^ HCl, in {qq NaOH, in distilled 

 water and in the sea water solutions mentioned above with 

 results as shown in table 2. 



An extraction was made from each of these species by heating 

 several grams of the plants which had previously been washed 

 for twenty-four hours, dried, and finely ground for two or three 

 hours at the temperature of boihng water, and then straining 

 through four thicknesses of muslin. The extract so prepared 

 was a pale straw^ colored viscous fluid which would not solidify 

 completely when cold but became very thick and viscous. The 

 extract from all of the species was fairly uniform in character. 

 Dried plates were made from 9 grams of agar and the extract 

 from 10 grams of the dry Gigartina exasperata. Trios of sec- 

 tions from these plates were sw^elled (see table 3). 



The analysis of the moisture-free material extracted from the 

 alga and extended with the agar gives the following: 



per cent 



Ash (salts) 15.89 



Gelatine like material 21 .05 



Agar-like material 63.06 



The washed and dried algae on analysis gave the following: 



Average values Moisture free 

 per cent per cent 



Ash (salts) 11.70 13.89 



Moisture 15.70 0.00 



Gelatine like material 14.95 17.73 



Carbohydrates agar like material 57.65 68.38 



The swelling of the dried sections, gives figures indicative of 

 the presence of a large proportion of an agar-like substance, a 

 smaller proportion of amino-acids, etc., and salts, and when the 

 extract was mixed with agar the imbibition in water, acid and 

 alkali, conforms to an expectancy of composition based on Mac- 

 DougaFs conclusions of the swelling of biocolloids, which is fully 

 confirmed by the chemical analysis. 



