( 204 ) 



These investigations, however, did not clearly show that the caffeine 

 when once formed again took part in the internal mutation processes ; 

 they rather pointed to a preservation of this substance as such and 

 in such cases where it was shown that the quantity of caffeine had 

 decreased, this might have, possibly-, I)een due to migration. 



We, therefore thought it desirable to subject plants containing 

 xanthine derivatives to a renewed investigation, to examine as many 

 species as possible and particularly to study the question whether 

 these xanthine derivatives are an intermediary or a final product of 

 the internal mutation. Coffea and Thea species were the only plants 

 investigated up to the present so we also included in our research 

 Kola acuminata Horsf. et Benn. and Theobroma Cacao both of w Inch 

 contain caffeine as well as theobromine. A stay at the Botanical 

 Gardens at Buitenzorg (Java) afforded us ample opportunity ^). 



At Buitenzorg many physiological experiments Avere made and 

 material collected for quantitative determinations, the results of which 

 will l)e i)ublislied later on ; qualitative and microchemical tests were 

 also made and of these a short description will be given below. 



First of all a few words as to the methods employed for the 

 detection of the xanthine derivati\'es in the \'arious parts. 



Behrens's method was used for i)lants containing caffeine only. 

 The parts were trituralctl in a mortar with quick lime and extracted 

 with 967„ alcohol. A few drops of the alcoholic solution were then 

 evaporated to dryness and the residue sublimed. The sublimate after 

 l)reathing on it then showed crystals of hydrated caffeine. 



In the case of plants containing both caffeine and theobromine 

 the parts were boiled with water slightly acidified with acetic acid. 

 The aqueous extract was filtered and precipitated with lead acetate ; 

 the filtrate after being neutralised with sodium carbonate was then 

 evaporated to dryness. Up to this stage the method proposed by 

 Behrens had been again used but the dry mass was not now heated 

 in order to sublime the xanthine derivatives but was extracted wdth 

 a little chloroform. Both xanthine derivatives passed into this solvent 

 and on evaporating the same they were left behind as well defined 

 crystals; sometimes the residue had to be first sublimed. 



Both methods are very delicate; traces of either caffeine or 

 theobromine may be detected. 



The investigation extended over the following i)lants : Coffea 

 arabica L., C. liberica Bull., C. stenophylla G. Don., Thea assamica 



1) Paullinia soibitis Mart, and Ilex paraguariensis St. Hilaire could nut be 

 investigated but we hope to do so on some future occasion. 



