IO2 



THE SCIENCE OF LIFE. 



dye, and one species, Leonora esculenta, found in the 

 Desert of Tartary, seems to fall from the sky as a mirac- 

 ulous manna. Men and beasts may be nourished on it. 



FIG. 36. Arrangement of tretraspores, in Carpocaulon mediterraneum : A. Entire 

 plant. B. Longitudinal section of branch. (N. B. Where only three tretraspores are seen 

 it is merely because the fourth did not happen to be so placed as to be seen at the same 

 view.) 



It is in the form of globules, varying from the size of a 

 pin's head to that of a hazel nut ; and as it grows freely, 

 not being attached to any substance, it is readily driven 

 by the wind from one place to another. 



The thallus of Lichens may be of various sizes, forms, 

 and colors. (Fig. 37.) Its fruit is called Apotheceia, and 

 forms cups, or shields, of various forms, often colored 

 bright red, yellow, gray, or black. When these are di- 

 vided by vertical sections they are found to contain a 



