SPURGE TRIBE ; CASSAVA, CROTON-OIL. ORDER URTICEJE. 495 



either as articles of food, or as valuable medicines. Thus the 

 root of the Jatropha Manihot contains a large quantity of starchy 

 matter ; and this is easily freed from the acrid juice, by pressure 

 and by heat, so as to be rendered quite wholesome ; and in this 

 state it constitutes a most important article of food, under the 

 name of Cassava, through a large proportion of the tropical coun- 

 tries inhabited by Man. The oil of the seeds of the Castor-Oil 

 plant is one of the mildest purgatives known ; but that of the 

 seed-coats is very acrid and dangerous. The seeds of the Croton 

 tiglium, and of the Jatropha Curcas, or Physic-nut of the West 

 Indies, also furnish an acrid oil, which is used in medicine as an 

 active purgative and emetic ; that of the Croton tiglium alone, 

 however, is ordinarily employed in this country as a medicine, 

 that of the Jatropha Curcas being now imported and brought 

 into use as a lamp-oil, for which it is well adapted. There are 

 some species, of which the juices are not strongly acrid ; but all 

 are suspicious. Besides these products, there is one that is 

 obtained in considerable amount from this order, the value of 

 which is every day becoming greater, from the new and varied 

 uses to which it is applied. This is Caoutchouc (. 367 9) ; 

 which, although partly obtained from a tribe to be presently 

 mentioned, exists in considerable amount in the Euphorbiacese 

 also. This order presents itself in the largest proportion in 

 tropical America. 



672. Another important group, also widely extended, and 

 affording many products of importance to Man, is that of URTI- 

 CEJE, the Nettle tribe. It will doubtless surprise those, who have 

 no previous botanical knowledge, to learn that the Fig, the 

 Bread-fruit, and the Nettle, belong to the same group, along with 

 the Hemp, Mulberry, and Hop. However much these differ 

 among themselves, they agree in certain general characters, which 

 distinguish them from all others. These characters may be most 

 readily seen in such plants as the common Pellitory, that grows 

 on wall-tops and in waste places ; in which the flowers are not 

 crowded together, as they will be shown to be in the Fig and 

 Bread-fruit, and in which the stinging hairs of the Nettle and its 

 allies are not present. Of the flowers of this plant, as in the whole 



