EUCALYPTUS OIL GLANDS. 209 



was made, but though the odour of geranyl acetate was 

 noticeable in the freshly cut surfaces, no clear evidence of 

 the presence of oil glands has yet been found, the bark 

 being in a very friable condition. The yield from the bark 

 of the latter species amounts to 0*12%. 



Although the distribution and number of the glands is 

 not of very great taxonomic value, yet, as pointed out in 

 this paper, certain variations do occur and without doubt 

 hold good throughout the distribution of the species. Again 

 it is quite possible to recognise certain differences in their 

 arrangement which would permit of a rough classification 

 into groups, of which some examples are given. 



In E. hcemastoma, E. goniocalyx, E. phlebophylla, E. 

 Moorei, etc., the glands are often distinctly flattened in 

 a direction at right angles to the leaf surface and occur 

 only in the palisade tissue, which in these species (isobi- 

 lateral) is directed towards either surface, and do not 

 encroach on the narrow zone of spongy mesophyll between. 

 In the case of E. intermedia and E. corymbosa for example, 

 the distribution is somewhat different, the major portion of 

 the gland being found in the spongy mesophyll, and is 

 usually narrower towards the epidermis. In E. piperita, E. 

 aggregata, E. hemipliloia, E, Smithii, etc., a type of gland 

 is found which extends right across the leaf section. In E. 

 robusta and E. resinifera the glands are comparatively 

 large and extend well into the mesophyll but are usually 

 directed towards the upper surface. In E. maculata, E. 

 citriodora, E. siderophloia and others the glands are small 

 and directed towards either surface in approximately 

 equal numbers. 



Although in almost every case an oil gland occurs 

 towards the surface of the leaf, the epidermal cells 

 forming the lid of the cavity being usually thinner than 

 elsewhere, this very often does not appear in section. This 



N— December 1, 1920. 



