162 



BOTANY. 



137, m, f, g), which is ensheathed by the Periblem,* which 

 soon becomes transformed into the cortical portion of the 

 root (x, r, Fig. 137). The epidermis is developed from the 

 region from which the root-cap grows, and, in fact, as will 

 be shown below, it is a continuation and modification of the 

 generating tissue of the root-cap. 



21O. In Fig. 138 the relation of the parts is even better 

 shown than in the previous figure. The central plerome 

 column is surrounded by a layer of active cells, the pericam- 



pc 



Fig. 138. Median longitudinal sectipn of the apex of the root of the buckwheat 

 (Fagopijrum eseulentiim). pc, pericambium, constituting the boundary of the plerome 

 column ; e, dermatogen ; between e andpc, periblem ; 7t, root-cap. Alter De Bury. 



bium (pc) ; outside of the latter lies the periblem, or young 

 cortical portion, and still outside of this the dermatogen 

 (e), which further back on the root becomes the epidermis. 

 The root-cap (h) lies entirely outside of, and is quite distinct 

 from, the back portions of the dermatogen, but near the 

 apex of the root there is a tract in which dermatogen and 

 root-cap apparently fuse into one. At this point the layers 



* Another of Hanstein'8 terms, from the Greek 7rep!6?.iyia, a cloak. 



