largely diluted; of the rough Cinchona-alcaloids. Thèse 

 testings were repeated with the same solutions to which 

 some drops of tannic acid had previously been added. This 

 was done because prehminary experiments had shown 

 the présence of both alcaloid and tannic acid in the same 

 cell; it was consequently of prime importance to study the 

 influence of the tannins on the reagents used. A beauti- 

 fully prepaired quantity of the Rough -alcaloid was ob- 

 tained by the kindness of mr. P. van Leersum, the func- 

 tionating Director of the Cinchona Gardens.This was 

 dissolved in slightly acidulated water and subsequently 

 used for microchemical tests. A drop of the solution was 

 mixed on the slide with a drop of one of the alcaloid- 

 reagents, examined under the microscope and the preci- 

 pitate drawn by means of the caméra lucida, both with 

 the mirror of the microscope turned on and off. 



The two rows to the left of Plates I, II and III of 

 the Dutch édition show thèse drawings in the natural co- 

 lors. They picture the précipitâtes obtained by ammonia 

 liquida, chromic acid, congo-red, eosine, chloride of gold, 

 iodine in watery solution, iodine dissolved in a solution of 

 iodide of potassium, double iodide of potassium and mer- 

 cury, bichromate of potassium, ferricyanide of potassium, 

 ferrocyanide of potassium, caustic potash, permanganate of 

 potassium, molybdate of ammonia, bicarbonate of sodium, 

 monocarbonate of sodium, phospho-molybdic acid, picric 

 acid, chloride of platinum, salycilic sodium and by corosi- 

 ve sublimate. 



Thèse reagents were consequently ail used to precipitate 

 the alcaloid in the cells of the leafstalk of Cinchona 

 Ledgeriana. As is seen from the two rows of pictures to 

 the right of Plates I, II and III of the Dutch édition 

 this succeeded with ail. Consequently the présence of the alca- 

 loid in the cells of the leafstalk of C. C. Ledgeriana lias been de- 



