GALLS AND CRYPTOGAMS. 321 



from the Chio Turpentine-tree (Pistada Terehinthua). 

 Galls called " Padwus" are produced in India on a 

 species of Tamarisk {Tamarix Fur as). Under the name 

 of Valonia, the acorn-cups of Quercus JSgilops, of the 

 Mediterranean region, are found in commerce, ako used 

 in tanning. 



324. Carrageen, or Irish Moss, is the Sea-weed or 

 Alga Chondrus crispus (division Carposporece). It grows on 

 the rocky North American and European Atlantic coast. 

 It is greenish-yellow to dark purple in color, and soft 

 and gelatinous in texture. It is washed and dried, when it 

 becomes horn-like, yellow, and translucent. It contains 

 thirty-three per cent, of mucilaginous substance, ten per 

 cent, of albuminoids, and fifteen per cent, of mineral con- 

 stituents, in which is a large amount of iodine. It 

 forms a jelly in twenty to thirty times its weight of 

 boiling water. Carrageen is used occasionally as an article 

 of food (blanc mange), and to thicken colors for printing 

 calico. In those regions where it grows, it is often em- 

 ployed as cattle food. The Dulse, Bhodymenia palmata 

 (division Carposporece), growing in places similar to the 

 last, is also used as human food, and as a remedy in scrofu- 

 lous complaints. 



325. SoeeeUa tinctoria is a foliaceous Lichen (division 

 Carposporece), which grows in tufts in rocks. It is found 



- all over the world, ofl«n growing on high perpendicular 

 clifis, from which it is collected by men lowered with 

 ropes. From this and other species of Lichens, Orchil 

 and Litmus are obtained. The former was at one time 

 very much used in dyeing, but has recently been largely 

 replaced by dyes of the coal-tar products. Litmus is used 

 as a chemical test for acids and alkalies. 

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