E. M. Watson. 
SO 
and E. tetragon a F. Muell. (10), E. oleo.sa F. Muell., E. eremo - 
phiJa Maiden and E. leptopoda Benth. (11), E. astringents Maiden 
and E. pyriformis Turcz. (12), E. ooneinmi Maiden et Blakely (13) and 
E. erythronema Turcz. (14). Mr. 11. V. Marr (priv. comm.) has made 
available the following information from investigations carried out by 
Messrs. Piaimar Ltd.: — E. uncinata Turcz. (yield up to 1.4 per cent., 
cineole content up to 75 per cent.) ; E. leptophylla F. Muell. (yield about 
1.2 per cent., 50 to 05 per cent, cineole) ; E. Sargenti Maiden (yield 1.4 per 
cent., about 60 per cent, cineole) ; E. Eormanii C. A. Gardn. (yield about 
1 per cent., about 45 per cent, cineole) ; E. eon glob ata (R. Br.) M'pidem, 
E. caly co gona Turcz. and E. incrassata Labill. give low yields of oil which 
contain only small amounts of cineole; E. gracilis F. Muell. (yield up to 
1.3 per cent., 60 to 75 per cent, cineole) and E. spathulata which yields up 
to 1.6 per cent, of oil of which 50 to 65 per cent, is cineole. 
Some of these oils are of obvious potential value as sources of medicinal 
eucalyptus oil. Others of similar value are E. erythronema , E. leptopocla 
and E. cone Inna. The initial cost of collecting leaves and small branches is 
a limiting factor in the successful exploitation of any oil bearing species 
and it is therefore essential that reasonably extensive, closely packed areas 
be available. It is this factor which has prevented the exploitation of some 
of our better species of Eucalyptus. A possible solution of this difficulty 
has been suggested by Mr. C. A. Gardner, who considers that species like 
E. erythronema , which has largely been cut out from the wheat belt, could 
be satisfactorily cultivated and could at the same time be made to serve the 
extremely useful purpose of preventing soil erosion. 
Other genera of the family Mvrtaceae yield oils which show some 
general resemblances to those of Eucalyptus , notably Melaleuca and 
Agonis. There are nearly 100 species of the genus Melaleuca in Western 
Australia, of which only six have been investigated, two of them for their 
cineole content alone. M. leucadendron L. is well known as the source of 
commercial cajuput oil. M. uncinata has been examined in some detail by 
Penfold (15) and K. E. Murray (16) and many samples have been exam- 
ined by Piaimar Ltd. (H. Y. Marr, priv. comm.). The species exists in at 
least three physiological forms, one of which grows preferentially around 
the low margins of lakes from Ballidu to Lake Grace. This form, which is 
generally arborescent, gives a low yield of oil which consists largely of 
terpenes and contains little or no cineole. A second form favours higher 
ground, particularly in granite country, and gives a much higher yield of 
oil of which from 75 to 85 per cent, is cineole. The third form resembles 
closely that described by Penfold from New South Wales. 
Murray (loc. cit.) has also examined the oils of M. lateriflora Benth. 
var. elliptic $ Benth. and M. rhaphiophylla Schau. The former contains a 
high proportion of hydrocarbons and an unidentified phenol ; the latter also 
contains a high proportion of hydrocarbons including a - and y -terpinene, 
probably p-evmene, sesquiterpenes and an unidentified hydrocarbon, 
together with the alcohol /\ ' -terpinenol-4 and sesquiterpene alcohols. 
The oils of M. I a xi flora Turcz. and M. Websteri S. Moore have been 
examined by Messrs. Piaimar Ltd. for their cineole content. 
The oil of Calythrix tetragona Labill. (17) has been investigated by Pen- 
fold, Ramage and Simonsen, and shown to consist largely of esters, notably 
eitronellyl formate and the methyl esters of geranic and probably citronellie 
