OALLSAND CRYPTOGAMS. g21 



from the Ohio Turpentme^tree {Pidaekf Terdiinth'^'). 

 Galls called " Pad^us" are produced in ladia on a 

 species of Tamarisk {Tamarix Fwas). Under the name 

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

 Mediterranean region, are found in commerce, also used 

 in tajining. 



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

 Alga Chondrus mspits' (diTision Oarpogporece). 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 (blane 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 CarposporecB), growing in places similar to the 

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

 lous complaints. 



325. RoceeUa tinctoria is a foliaceous Lichen (division 

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



- all over the world, often growing on high perpendicular 

 cliffs, 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. 

 21 



