CRUDE DRUGS. 689 



Constituents. — From 55 to 90 per cent, of carrageenin, a 

 mucilaginous principle which is but slightly adhesive ; about 10 

 per cent, of proteids, and 10 to 15 per cent, of ash, consisting of 

 calcium oxalate and compounds of sodium, potassium, magnesium 

 and calcium with chlorine, iodine, bromine and sulphur. 



Allied Plants. — Gigartina mamillosa (Fig. 278a) somewhat 

 resembles Chondrus, but it is most abundant north of the 

 region where Chondrus is gathered and so rarely enters com- 



FiG. 278a. Gigartina mamillosa, a red seaweed closely related to Chondrus crispus, 

 showing dichotomously branching thallus bearing at the upper part numerous cylindrical 

 outgrowths in which the fruit bodies (cystocarps) are found. — After Kutzing. 



merce. It is distinguished by having the cystocarps borne on 

 short, tuberculated projections or stalks scattered over the upper 

 portion of the segments. 



For other Marine Algse used in medicine, see p. 16. 



An ARTIFICIAL GUM is prepared by adding starch to the muci- 

 lage of chondrus, and is said to be a good substitute for acacia 

 and may be employed as a base for fixing colors in fabrics. 



CETRARIA.— ICELAND MOSS.— The entire plant of 

 Cetraria islandica, one of the Ascolichens (Fig. 26, illus. 5), 



44 



