1 1 



whether growing only a few feel from each othei 01 miles apart, rhe results 

 here recorded are a good illustration of the constancj of chemical onstituents 

 in oils of the same species. 



I he low ester value, the absence of an excessive amount of volatile 

 aldehydes, together with the large amount of cineol are characteristic of the 

 oil oi this species. Perhaps /:'. obliqua is even a better illustration <>t this 

 chemical agreement as can he seen under that species. 



Many other instances might be mentioned in which this constancy of 

 chemical constituents i- demonstrated, not only from our own results, but also 

 in connection with those obtained by previous observers, although unfortunately, 

 precise data in this connection are often wanting; but those mentioned above 

 are sufficient to -I" w that, when no error has been made in the botanical 

 diagnosis, and no mixing of the leases has taken place, the chemical results will 

 be unmistakable also. 



If it is possible io show that this is so, then the corollary must be that 

 the same species of Eucalyptus will give practically the same oil. and consequently 

 the commercial aspect of the question is placed upon a sure foundation ; not 

 only from the commercial side of the question is this important, but this 

 constancy of constituents must be taken into consideration in the diagnosis 

 of doubtful species. Supposed allied forms that do not individually 

 show chemical constituents in (dose agreement cannot consequently be the same 

 species. 



A- an instance of how this confusin \ of species has appealed to other 

 workers on Eucalyptus oils, the remarks of Gildemeister and Hoffmann, in the 

 work above quoted, may be mentioned. Two oils supposed to be from E. 

 dealbata, were under review, and thej saw " that it is impossible for it " (the 

 second sample) "to have c me from the same plant " (as the first sample). 



We have received much help towards settling doubtful botanical points 

 since the discovery of this constancy in chemical constituent- was made, the 

 results assisting much towards demonstrating differences between the several 

 species, which otherwise, could not have been decided so satisfactorily. When 

 these differences have been detected, further research has shown well marked 

 morphological characters to be also presenl in fact, so distinct that the species 

 cannot again be confounded with others; or, in oilier words, we have learned 

 its history and found its place in nature The exceptions to this are verj 



As a further evidence ol the comparative constancj of Eucalyptus specii 

 one nerd onlv look to their introduction into other countries, where they 

 retain all their physical characters and morphology, as obtains in their native 



habitat , 



