5 



Wionstrated bij the aid of some twenty reagents. 



It was demonstrated at the same time that alcaloid 

 and tannic acid are frequently found in the same cell 

 most probably the alcaloid is présent as a tannic acid sait. 



In many cases it was shown simultaneously that the al- 

 caloid is dissolved in the cellsap. 



Yet, thèse reagents are not ail of equal value for our 

 purpose. Many become unclear owing to the présence of 

 tannins, others penetrate badly into the cells, others again 

 have a destroying influence on the cellwalls or on the proto- 

 plasm, thus causing the alcaloid to escape from the cells etc. 



The reagent best adopted to our needs proved to be a 

 solution of iodine in ioclide of potassium. 



It was this solution that was mostly used but when 

 the least bit of doubt was caused by the aspect of the pre~ 

 cipitate thus obtained, or if the absence of a precipitate made 

 us wonder, other reagents where always used to put the re- 

 mit obtained by the iodine solution to the test. . 



C. Concentration and mode of using the 

 Iodine — solution (!) 



The most practical way of making the Iodine -solution 

 is thus: In a certain quantity of water a rather large 

 quantity of iodide of potassium is dissolved, how large a 

 quantity is of little importance provided it be not too lit- 

 tle. It is however of prime importance that this solution be 

 consequently absolutely saturated with Iodine as free Io- 

 dide of potassium dissolves the alcaloid. 



This solution is kept in stock. 



Shortly before using, so much of it is mixed with water 

 that this solution, poured into a watchglass is of the colour 

 of vermouth. To obtain comparable results a solution of the 



(*) So called for shortness' sake. 



