375 



purified crystallised eudesmol to slowly change its character, until eventually 

 it forms a thick liquid mass, and with one exception all our samples have remained 

 in this condition after settling down. Although this tendency of the separated 

 crystallised eudesmol to revert to the semi-liquid form is so pronounced, yet 

 under some conditions which at present are not clear this change has not taken 

 place, and we have in our possession one sample distilled from the oil of 



PLATE LXXXV. 



3rd stage. 



2nd stage. ' 



, ist stage. 



ILLUSTRATING THE UNSTABLE NATURE OF EUDESMOL . 

 FROM EUCALYPTUS OILS, IN THREE STAGES. 



(For description see page 376.) 



E. camphora twenty years ago, and thus separated in the crude condition, which 

 has remained in the crystallised form all that time. In other cases eudesmol 

 prepared from the oil of this species has liquefied after a few months. We also 

 possess one sample of eudesmol separated from the oil of E. Macarthuri, which 

 has remained in the crystallised condition for two years, and at present shows 

 but little signs of alteration, whilst other specimens from the oil of this species, 

 distilled at varying times of the year, have liquefied after a few months, although 

 they had been prepared in exactly the same manner. As shown later it is 

 possible to partly change this liquefied eudesmol back to the crystallised form. 



Under natural conditions crystallised eudesmol appears to occur more 

 frequently, and in greater abundance, in the oils of species belonging to the more 

 recent groups in the evolutionary sequence of the genus, as the '' Peppermints," 



