62 R. T. BAKER AND H. G. SMITH. 
mixing of the leaves of species when used commercially 
will, of course, give no constant product and detract from 
the value of any standard which might be formulated. 
The following species are investigated :—(1) M. 
thymifolia, Sm. (2) M. linariifolia, Sm. 
(1). Melaleuca thymifolia, Sm., B. FI. iii. p. 134. 
‘*Thyme-leaved Tea Tree.”’ | 
This was one of the very first Melaleucas described from 
Australia, the description being published by Smith in the 
Transactions of the Linnean Society in 1797. It is recorded 
now from the coast ranges and districts from Southern 
Queensland to the Blue Mountains and Port Jackson, in 
the neighbourhood of which it is rather plentiful. It is a 
small shrub with glabrous leaves and inflorescence; the 
flowers are purple in colour and quite characteristic of the 
species, and on this account as well as its valuable oil 
constituent it is a plant worthy of cultivation. The leaves 
appear almost veinless but are thickly studded with oil 
glands, which are scattered irregularly throughout the 
whole underside of the leaves, but quite absent from the 
upper or concave side, a provision probably of nature to 
protect them from the volatilising influence of the sun’s rays. 
Histology—The transverse vertical section of the leaf 
blade here given, affords a good type of histological leaf 
structure. The ventral and dorsal surfaces are covered 
with only one well defined layer of epidermal rectangular, 
elongated cells. On the dorsal side and round the edges 
of the leaf the epidermal cells appear to have the stronger 
walls, as those on the ventral surface have evidently a 
thinner wall structure as they break away in cutting. 
Stomata are more numerous on the upper surface, giving 
it a broken appearance in section, and are more clearly 
shown than generally obtains in most leaf sections. The 
guard cells are in shape like a pair of anthers and strongly 
