236 BIOCHEMICAL SYSTEMATICS 



part of the range of the species was reqmred to answer this question. 

 As a result of such investigations Baker and Smith were impressed 

 with the constancy of oil characters within a species: 



The theory has often been advanced that the chemical constituents of 

 the same species vary in different localities, but this idea is not verified 

 by our experiences as regards the Eucalypts, as they do not show these 

 differences in chemical constituents that might perhaps be expected 

 from differences of soils or localities. The reverse may possibly be 

 accounted for by the natural selective, ecological peculiarities shown in 

 many instances by the species themselves, as it is remarkable how a 

 certain species will flourish on a particular geological formation and 

 become singular to Hke formations, while at the same time objecting 

 to those entirely different. However that may be, those influences do 

 not appear to act detrimentally, or to interfere in any way with the 

 practical constancy of results. 



It is apparent now that more variation in oil character existed 

 than was recognized by Baker and Smith, especially among the in- 

 dividuals of a population. For example, in discussing the oil characters 

 of Eucalyptus dives they noted that the constancy of oil characters 

 exhibited by Eucalyptus species generally also apphed to E. dives. 

 Components of E. dives oil are crude oil, largely phellandrene with 5 

 to 8 per cent cineole and some piperitone. Another fraction consisted 

 largely of the peppermint ketone, piperitone. But, Penfold and 

 Morrison (1927) also described major variations in the oil character 

 of E. dives. Ordinarily this species yields oils with 45 to 50 per cent 

 piperitone. Yet, some plants identical to typical E. dives yielded as 

 low as 8 per cent piperitone. In fact, there had been some complaints 

 that differences in the piperitone concentration were the fault of the 

 distillation techniques if not the result of adulteration. The following 

 picturesque statements from Penfold and Morrison indicate that 

 significantly different oil characters did indeed occur in two plants 

 which were morphologically indistinguishable: 



Then again whilst engaged in field service during the end of December, 

 1924, repairing a punctured tyre of the car by which we were travelling 

 led us to examine a patch of trees of this species growing close to the 

 Main Southern Road about 18 miles on the Sydney side of Goulburn. 

 The observation was made of two trees growing together, indistin- 

 guishable from one another by both botanist and bushman, but each 

 containing a different essential oil. On crushing the leaves between the 

 fingers, one yielded the typical phellandrene-piperitone odour, whilst 

 in the other the odour of cineol-phellandrene-terpinol was most 

 pronounced. 



