748 ALG^. 



times its weight, boiled with it for ten minutes, solidifies on cooling to 

 a pale mawkish jelly. 



Microscopic Structure — The tissue of Ghondus crispus is made 

 up of globular or elongated, thick- walled cells. The superficial layers 

 on both sides of the lobes constitute a kind of peel, easily separable in 

 microscopic sections. The interior or medullary part exhibits a much 

 less densely packed tissue formed of larger cells. The larger cavities of 

 this tissue contain a granular mucilaginous matter, assuming a slight 

 violet tinge on addition of iodine. In water however, the cell-walls 

 swell up so as to form a gelatinous mass, in which separate cells can at 

 last be scarcely distinguished.^ In the fresh state, its cells also contain 

 granules of chlorophyll imbued with a red matter, termed Phyco- 

 erythrin. But by washing and exposure to the air, these colouring 

 substances are removed or greatly altered, and are no longer visible in 

 the commercial drug. 



Chemical Composition — The constituents of carrageen are those 

 generally found in marine algae, especially as regards the mucilage. 

 This latter is insoluble in an ammoniacal solution of copper (Schweizer's 

 test) ; by the action of fuming nitric acid, it yields, in common with 

 gum, an abundance of mucic acid. The mucilage of carrageen, like 

 many similar bodies, obstinately retains inorganic matter ; after it had 

 three times been dissolved in water, and as many times precipitated 

 with alcohol, we found it still to yield the same quantity of ash as the 

 raw drug itself, that is to say, more than 15 per cent. The mucilage, 

 perfectly dried, is a tough hornj'^ substance, of a greyish colour; it 

 quickly swells up in water, forming a jelly which is precipi table by 

 neutral acetate of lead. 



By boiling carrageen for a week with water containing 5 per cent, 

 of sulphuric acid, Bente (1876) obtained crystals of Icevulinic acid, 

 C'H^O^, and an amorphous sugar. The former is also afforded by 

 cellulose of pine wood and by paper. 



According to Blondeau,^ the mucilage of carrageen contains 21 per 

 cent, of nitrogen and 2'5 of sulphur, a statement which we are able to 

 point out as erroneous. We find in it no sulphur, and only 88 per 

 cent, of nitrogen. The drug itself yielded us not more than 1-012 per 

 cent, of nitrogen. 



When thin slices of the plant are treated with alcoholic potash, and 

 then after washing left for 24 hours in contact with a solution of iodine 

 in potassium iodide, they acquire a deep blue ; yet, starch granules are 

 not found in this seaweed. Lastly in connexion with carrageen may 

 be mentioned Fucusol, an oily liquid isomeric with furfurol, obtained by 

 boiling seaweeds with dilute sulphuric acid. 



Commerce — The plant is collected on the west and north-west 

 coast of Ireland : Sligo is said to be a great depot for it. Carrageen 

 of superior quality is sometimes imported from Hamburg. 



The largest quantities of carrageen, sometimes half a million pounds 

 a year, are gathered near Mi not Ledge lighthouse, Scituate, Plymouth 



^Alcohol, glycerin or a fatty oil are the ^ Jourii. de Pharm. ii. (1865) 159. 



liquids most suited for the microscopic 

 examination of this drug. 



