8 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



the summit of the segments; somewhat cartilaginous; having a 

 slight saline odor and a mucilaginous, saline taste. 



One part of Chondrus when boiled for ten minutes with 30 parts 

 of water yields a solution which gelatinizes on cooling, and is not 

 colored blue by iodin test-solution (absence of starch); nor precip- 

 itated by alcohol (distinction from true plant gums) ; nor precipitated 

 by tannin (distinction from gelatin) ; nor precipitated by lead acetate 

 (distinguishing it from pectin). 



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

 aginous principle which is but slightly adhesive; about 10 per cent 

 of proteins, and 10 to 15 per cent of ash, consisting of calcium oxalate 

 and compounds of sodium, potassium, magnesium and calcium 

 with chlorin, iodin, bromin and sulphur. 



Allied Plants. Gigartina mamillosa somewhat resembles Chon- 

 drus, but it is most abundant north of the region where Chondrus is 

 gathered and thus rarely enters commerce in the drug collected in the 

 United States. It is not unusual, however, in the imported article, 

 and is distinguished by having the sporangia borne on short, tuber- 

 culated projections or stalks scattered over the upper portion of the 

 segments. 



An artificial gum is prepared by adding starch to the mucilage 

 of Chondrus, and is said to be a good substitute for acacia, and may 

 be employed as a base for fixing colors in fabrics. 



Literature. Anatomy and Constituents by Tunmann, Apoth. 

 Zeit., 1909, p. 151. Morphology and Collection by Kraemer, Amer. 

 Jour. Pharm., 1899, p. 479. For illustrations see Kraemer's Applied 

 and Economic Botany. 



AGAR-AGAR. Japan or Chinese Gelatin. The dried mucilaginous 

 substance obtained from several species of Gelidium, and Pterocladia 

 capillaceum, red algae (Rhodophycese) growing along the Eastern 

 coast of Asia. The algse are collected and prepared in much the 

 same manner as Chondrus. The bleached material is then boiled 

 with water, strained through a cloth, and the mixture allowed to cool. 

 It is finally dried in the sun during rather cold weather. It is used 

 to some extent in medicine, but its chief use is in the preparation of a 

 solid culture medium which is extensively used in bacteriology. 



Description. Mostly in bundles, consisting of thin, transparent, 

 membranous, agglutinated pieces, 4 to 6 dm. in length and 4 to 8 

 mm. in width; externally oyster-white or brownish-white, shiny; 

 tough and brittle when dry; odor slight; taste mucilaginous. 



Inner Structure. A granular or mucilaginous mass in which are 

 imbedded the frustules of one or more diatoms, those of Arachnoidis- 



