THE MUSHROOM TRIBE. 285 



Richardson, and Back, were for a long time able to 

 procure in the horrible countries they so fearlessly 

 visited in the cause of science ; Reindeer Moss (Cla- 

 donia rangiferina) is the winter food of the Rein- 

 deer of the Laplanders ; Iceland Moss (Cctraria is- 

 landica) furnishes a nutritive food to the invalid ; 

 and finally the production of Orchil, by Roccella 

 tinctoria is an indication of the value of some species 

 to the manufacturer as dyes. 



Very closely related to Lichens, and standing 

 almost parallel with them in the scale of organization, 

 are Fungi, or the Mushroom tribe (Plate XXV. 3.), 

 plants with which we are best acquainted from our 

 knowledge of the common eatable Mushroom, but 

 which have almost an endless diversity of form and 

 organization. In this, however, they are all agreed, 

 that while the thecal of Lichens are placed in shields 

 or receptacles, which are exposed to the air, those of 

 Fungi are in all cases concealed by a covering of 

 some kind. To give you any thing like an accurate 

 notion of the many difi'erent appearances of Fungi, 

 would be wholly impracticable in a work of this 

 kind ; Dr. Greville's Scottish Cryptogamic Flora 

 should be your guide, if you would dip deeply into 

 the mysteries of their organization. They vary from 

 simple cells that hardly adhere, to chains of cells 

 which resemble a necklace, thence to hollow balls, 

 infinitely minute, that are generated in the living 

 substance of leaves and stems, which they afilict 

 under the names of mildew or blight, these again are 

 developed in subterranean masses of cellular sub- 



