— 134 — 



yCB. 2 -CO /CH., /CH.-CHOH /CH^ /CH=COH /CH, 



CH 3 .CH NcH-CH CH 8 .CH ^CH-C CKL-C ^C'CH 



X CH 2 -CH 2 N CH 3 X CH 2 -CH 2 X CH 3 X CH— CH CH 3 



Menthone Menthol Thymol 



Recently Ciamician and Silber 1 ) have converted menthone, 

 by exposure to light, into aliphatic decylic acid and into mentho- 

 citronellal. 



CH CH CHO-CH, 



>CH • CH 2 - CH 2 - CH 2 - CH • CH ? . COOH )C :CH >CH . CH, 



CH/ " CH 3 / \ / 



CH s 3 CH 2 -CH 2 



Decylic acid Menthocitronellal 



The iso-compounds ofpulegone andpulegol have not been examined 

 with regard to their action; according to W. Lindemann 2 ), pulegone 

 and puiegol are identical in their action. If the reduction of pulegone 

 is carried still further, the C : C-group in puiegol is converted into 

 C H • C H, and menthol is formed, which is much less toxic than 

 puiegol. For this reason it is undoubtedly to the double bond in the 

 side-chain that the toxic action of pulegone and puiegol is due. 



The derivative designated by C. Harries and G. Roeder 3 ) as 

 a-isopulegone is converted quantitatively, by prolonged standing in 

 alcoholic solution with baryta water, into dextrorotatory pulegone. 

 From this it would appear that a different behaviour of the iso- 

 compounds with regard to the behaviour in the organism cannot be 

 expected. 



It is particularly interesting that the series of compounds here 

 discussed stands in such close relation to thymol; menthol is a hexa- 

 hydrated thymol. Thymol differs from the phenols by a specially 

 feeble toxicity, and is known as a constituent of numerous essential 

 oils. It does not appear impossible that in the plant itself conversions 

 of phenols into the camphor-group also take place. 



With regard to the bromatological experiments carried out by 

 Zwaardemaker with musk one and other odoriferous substances, see 

 under Musk, p. 107. 



PhytO'physiological Notes. 



We have hitherto discussed under this heading the work dealing 

 with the isolation of glucosides splitting off hydrocyanic acid, if at 

 the same time benzaldehyde, or an allied body present in essential 



x ) Berl. Berichte 40 (1907), 2421; comp. the present Report p. 123. 

 2 ) Arch. f. exp. Pharmakol. 42 (1899). 

 s ) Berl, Berichte 32 (1899), 3371. 



