3 



Part. I. The localisation of the alcaloid. 



A. Method. 



The method here followed is an adaptation of the gêne- 

 rai methods for the localisation of alcaloids described by 

 L. Errera and his pupils. i 1 ) 



Several reagents precipitate the alcaloids in Cinchona 

 cells but none of them is typical for the alcaloids exclusi- 

 vely, albuminous substances giving very similar reactions. 

 Bij good fortune there is a way however to distinguish 

 them neatly, it is based on the solubility of alcaloids and 

 the insolubility of albuminous substances in acid alcohol. 



A precipitate caused by the alcaloid reagents in the Cin- 

 chona cells consequently indicates the présence of alcaloid 

 or that of an albuminous substance. To décide this, we 

 make two sections of the organ under investigation; the 

 one is put at once under the alcaloid treatment, the other 

 is first extracted by means of acid alcohol. The one section 

 consequently contains the alcaloid in normal quantity, the 

 other is entirely free from it. 



Treating both with the same reagent, in the same con- 

 centration and obtaining a precipitate in each we may safely 

 conclude this precipitate to be due to the présence of an 

 albuminous substance. If on the other hand no precipitate 

 appears in the extracted section, while a profuse one is for- 

 med in the non -extracted one, it is caused by an alcaloid. 



B. ChOICE MADE OUT OF THE DIFFERENT REAGENTS. 



To find th.3 most suitable reagents, that is to find those 

 wliich gave the most eonspicuous précipitâtes a large num- 

 ber of reagents was tested macrochemically on solutions, 



i 1 ) Errera., Maistriau et Claulriau. Premières recherches sur la localisation 

 «t la signification des alcaloïdes dans les plantes.. Bruxelles 1837.— 



