P.) 



are eut off from further nourishment by slanting corkla- 

 yers, alcaloid is met with occasionally, but always in small 

 quantities. 



c. The Root. 



If one brings a longitudinal section of a roottip in the 

 iodinesolution the meristema stains a dark brown at onee. It 

 looks exactly as if much alcaloid were présent in it. A 

 contrôle -expeiïment however shows tins colour to be due to 

 albuminous substances and not to alcaloids. 



The rootcap contains no alcaloid as little as do the epi- 

 derm is or the roothairs. Yet one can obtain sections in which 

 the peripheral celllayer contains alcaloid (fig. 143 Pl. XVII, 

 fig. 145 PL XVIII). In thèse sections the epidermis lias 

 allready been thrown off: the peripheral layer consequently 

 is no epiderm, luit the formerly subepidermal layer now 

 called exoderm. Even on a much younger stage tins 

 subepidermal layer contains alcaloid (fig. 144 Pl. XVIII, fig. 

 140 Pl. XVII, fig. 147 Pl. XVIII). This subepidermal layer 

 may contain alcaloid up to a point very near to the tip of the 

 root, or the alcaloid may begin at a much further distance 

 from the latter; roots which are in a comparative period 

 of rest apparently have the alcaloid very close to the meris- 

 temal tip, those growing rapidly not in so young a part. 



The primary rootbark contains no alcaloid, nor does the 

 central cylinder, hesides in the exoderm it is found in such 

 young roots in the endoderm (fig. 141, 142 Pl. XVII) or and 

 this is more generally the case in a layer immediately out- 

 side of the endoderm (fig. 140. Pl. XVII). In a somewhat 

 older root, beginning to throw of its epiderm (fig. 141 Pl. 



XVII) some little alcaloid appears in some of the primary 

 bark cells, which later on may increase yet (fig. 145 Pl. 



XVIII) . In the centralcylinder no alcaloid is found neither in 

 the parenchyma nor in cambium or pericambium (peiicycle). 



