8 



a cross-section would give much plainer results and one 

 regrets to be unable to obtain one. 



In such cases I frequently obtained very good results 

 by cutting across the leaf stalk under a diluted Iodine- so- 

 lution thus causing the leaf by means of its transpiration 

 to suck in the Iodine -solution. Yes, ba*ed on Strasburgers 

 investigation concerning the mounting of poisonous solutions 

 in trees, I even made large branches suck in the solutions, 

 thus obtaining very good results indeed. 



If one subsequently makes cross -sections of suchanorgan 

 it does not matter wether the cells are opened or not, the 

 precipitate remains at the spot where it was formed 

 provided one's razor be sharp enough. 



A sharp razor cuts through the precipitate and leaves it in 

 position, a blunt one tears it out of the cells. 



D. Choice of Cinchona species. 



At first Cinchona Calisya Ledgeriana was used exclusi- 

 vely, later it was fonnd that many points were much 

 clearer in C. succirubra consequently that species was 

 investigated also and the results compared. 



E. The localisation op the alcaloid. 



A. The leaf. 



1. The epidermis. 

 At no time does the epidermis contain any alcaloid, nei- 

 ther in the young nor in the old leaf. It is true one 

 obtains occasionally a reaction which might lead one to 

 accept the présence of traces of alcaloid, but even then it 

 occurs only in a few of the epidermal cells. Anyhow, if pré- 

 sent at ail, it is of no significance whatever, neither do 

 the hairs or closing cells of the stomata contain any 

 alcaloid. 



