74 PROCEEDINGS OF SECTION B. 



i^ive a product practically constant in constituents, which only 

 vary slightly in amount at any time. It is thus seen that the 

 influences which have brought about distinctive characters in the 

 external features of the several plants, have also exerted corre- 

 sponding influences on the constitution of their various chemical 

 products. 



The Australian Myrtaceous plants are evergreen, so that the 

 particular constituents which characterise the oils of individual 

 species are continually in a state of formation. With the Euca- 

 lypts particularly it can be demonstrated that in the very earliest 

 seedling leaves the characteristic oil constituent of that species is 

 formed. This can be well shown with the odoriferous constituents 

 such as citronellal, in the seedlings of E. citriodora, or of geranyl- 

 acetate in the corresponding young seedling leaves of E. Macarthuri. 

 The formation of these odoriferous constituents, characteristic of 

 the species, is thus brought about very early in the life history of 

 the plant, and remains persistent throughout its whole growth. 

 One would naturally expect, therefore, to find a certain constancy 

 in the molecular arrangement of the constituents of the essential 

 oils, corresponding to the constancy of botanical features which 

 identify the plant. That there is often a close relationship 

 between the constitution of the essential oil and the morphological 

 characters of the plant is now certain, and is well shown by the 

 three types of leaf venation in the genus Eucalyptus, each type 

 being indicative of the predominance of a particular oil con- 

 stituent. It is thus seen that the chemical characters of any 

 particular species should be of a fairly constant nature, and in 

 practice this is found to be the case, so that when once the con- 

 stituents of the chemical products of any Myrtaceous plant have 

 been accurately determined, a basis has been established for their 

 possible commercial utilisation, if this is promising. 



Myrtaceous plants generally, and the Eucalypts in particular, 

 are as a rule very tenacious of life, and under ordinary conditions 

 are difficult to destroy by merely cutting them back, as they soon 

 shoot out again with an abundance of new growth. The oil from 

 this new growth is in agreement with that from older trees, and 

 Is often obtainable in greater quantity, so that if a plantation was 

 established, a supply of a particular product would be assured. 

 By the indiscriminate waste of naturally growing material the supply 

 will in time become exhausted, particulaii}^ in cases where the 

 land is cleared for agriculture, so that the question of cultivation 

 naturally demands consideration. 



It seems beyond question that the products from systematically 

 cultivated Myrtaceous plants could be produced at a price with 

 which the suppliers from naturally growing trees could in many 

 instances hardly hope to compete. Unfortunately, the idea of 

 cultivating natural Australian plants is one that the average 

 Australian takes little interest in. The country is so vast, and so 

 sparsely populated, and has such an abundance of vegetable 

 growth, that he is content to destroy the indigenous trees rather 



