I i 



whether growing only a few feet from each other or miles apart. The results 

 here recorded are a good illustration of the constancy of chemical constituents 

 in oils of the same species. 



The low ester value, the absence of an excessive amount of volatile 

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

 oil of this species. Perhaps E. obliqua is even a better illustration of this 

 chemical agreement as can be seen under that species. 



Many other instances might be mentioned in which this constancy of 

 chemical constituents is 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 show that, when no error has been made in the botanical 

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

 be unmistakable also. 



If it is possible to 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 close agreement cannot consequently be the same 

 species. 



As an instance of how this confusing 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 they say, " that it is impossible for it " (the 

 second sample) " to have come 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 constituents 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 present in fact, so distinct that the species 

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

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

 rare. 



As a further evidence of the comparative constancy of Eucalyptus species, 

 one need only look to their introduction into other countries, where they 

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

 habitat. 



