*I44 



PLANT ORGANS OR PARTS OF PLANTS. 



minute side rootlets. The vessels vary widely, may be 

 thick- walled, and the fragments usually show traces of the 

 pores, which are slightly bordered. Sometimes spiral 



vessels are found. Small 

 fragments of woody paren- 

 chyma containing starch 

 grains are also met with. 



JALAP. 



Jalap is the tuberous 

 root of Ipomoea Jalapa, a 

 native of damp shady 

 woods of eastern Mexico 

 and the surrounding pro- 

 vinces. It is now also in 

 cultivation in Jamaica 

 and in the Nilgherry 

 mountains of India. Jalap 

 is gathered at all times of 

 the year, hence there is a 

 great variation in its con- 

 stituents, especially the 

 starch, some specimens 

 being very rich in this 

 ingredient and on account 

 of this generally less valu- 

 able. These specimens 

 break with a mealy frac- 

 ture. Others contain very 

 little starch, have a tough 

 fracture, and are dark- 

 brown and shiny on the 

 broken surface. As a 

 rule, such are to be pre- 



FiG. 36. — Jalap. 

 Cross-section through the outer 

 portion of jalap tuber: k, Cork; m, 

 milk tubes; c, cambium; h, vessel 

 portion (Tschirch). 



f erred. The powder is dark-brown. 



The more prominent microscopical constituents are 



