11 



In normal green adult leaves of G. S. the alcaloid bas 

 easily been demonstrated by means of the iodine potassium- 

 solution (fig. 99 Pl. VIL fig. 107 Pl. VIII) picric acid, plati- 

 nuin chloride, corrosive sublimate, double iodine of potas- 

 sium and mercury and bicarbornate of sodium. 



The same thing holds true for leaves of Cinchona Ledgeri- 

 ana but the co-occurrence of a dextrine and of an albuminous 

 substance make it exoeedingly difficulb to demonstrate its 

 présence. For particulars I must refer to the dutch text. 

 (fig. 102 Pl. VIII shows the alcaloids in the leaf of C. Led- 

 geriana, fig. 103 the dextrine albuminous substance, fig. 104 

 also, fig. 105 and 106 show the yellow and brown preci- 

 pitate by molybdaenic ammonia in the epidermal cells, the 

 colorless alcaloid-precipitate in the hypoderm). 



4. Midrib, veins and vascular-bundles of the leaf. 



The xylem-part contains no alcaloid, the colorless, re- 

 duced sievetubes „Uebergangs-Zellen" of thefinest veins 

 neither, nor does the mesophyllsheath of thèse finest veins. 



The mesophyll cells bordering on the mesophyll sheath, 

 on the other hand, contain much alcaloid. 



In somewhat thicker veins we find between the xylem 

 and the „Uebergangszellen" some layers of longitudinal! y 

 stretched cells forming an approach to a phloëm part but 

 in which sievetubes can not yet be distinguished. Thèse 

 cells contain no alcaloid. In the mesophyll sheath of such 

 somewhat thicker veins alcaloid eould be demonstrated 

 (fig 115 Pl. IX). 



1 n somewhat larger veins sievetubes are présent, thèse 

 contain no alcaloid nor do their conducting cells. The vas- 

 cular bundle of thèse thicker veins is not surrounded by 

 the mesophyll directly but enclosed in a coloras paren- 

 chyma with collenchyma at the periphery. This tissue pro- 

 trudes at both sides of the leaf and it is this tissue which 



