- 140 — ^ 



In none of the plants examined by them, Curtius and Franzen failed 

 to find the aldehyde, and it is therefore permissible to assert with reasonable 

 confidence that it occurs in all green plants. 



Its occurrence is closely allied with the assimilation of carbonic acid, 

 for Reinke and Kratschmar have shown that the distillates of plants which 

 had been kept in the dark for some days no longer possessed any power 

 of reduction, whereas that power returned as soon as they were again 

 exposed to light. The aldehyde is probably an intermediary product in 

 the formation of other bodies which are essential to plant-life. 



All the possible reduction-products of «,/?-hexylenic aldehyde have 

 been shown to exist in the vegetable kingdom. A hexylene alcohol, 

 probably a, /2-hexylene alcohol, has been discovered by van Romburgh 1 ) 

 in tea oil. This hexylene alcohol is readily convertible into hexylic aldehyde 

 (caproic aldehyde) by migration of the double bond. We have shown 2 ) 

 that it is probable that the same alcohol occurs in oil of Eucalyptus 

 Globulus. Further reduction of the caproic aldehyde results in hexyl 

 alcohol which, in the esterified form, occurs in certain essential oils. 



It is impossible for us here to enter into details of the exceedingly 

 noteworthy observations by the authors in the possible conversions of 

 the aldehyde into carbohydrates. For these details we must refer to the 

 original paper. 



In order to obtain a knowledge of the volatile acids which exist in 

 hornbeam leaves, Curtius and Franzen 3 ) subjected the finely ground leaves 

 to steam-distillation and added to the distillate cold saturated baryta- 

 water until it gave a faintly alkaline reaction. The whole mixture was 

 then distilled by steam, the volatile acids thus being left behind in the 

 distillation residue in the form of baryta-salts. The solution of the baryta 

 salts was further evaporated in vacuo, diluted with phosphoric acid, and 

 treated with steam until the distillate ceased to give an acid reaction. 

 The distillate was then extracted with ether and the aqueous and ethereal 

 solutions were worked up separately. The aqueous solution was found 

 to contain formic and acetic acids. The ethereal extract contained traces 

 of a hexylenic acid which, however, was not the acid corresponding to 

 «,/#-hexylenic aldehyde, but was probably identical with the acid C 6 Hio0 2 

 which has been prepared from croton oil by Schmidt and Berendes 4 ). 

 It is probable that hornbeam leaves also contain one or more homologues / 

 of this acid. 



The liquid which had been distilled off from the baryta salts of the 

 acids had a pronounced odour of «,/?-hexylenic aldehyde. With the object 



2 ) Report of the Botanical Gardens at Buitenzorg, 1895, 119. Also see Report April 1897, 40. 

 2 ) Schimmel's Bericht April 1888, 18. 



8 ) Sitzungsberichte der Heidelberger Akademie der Wissenschaften. Sect. B, 1 st paper. 

 from a copy kindly sent to us. 



*) Liebigs Annalen 191 (1878), 121. 



