514 EVOLUTION OP THE EUCALYPTS, 



characters, the chemical constituents of the oils vary greatly. 

 Thus we find E. Icevopinea, E. dextropinea, and E. Wilkinsoniana 

 give pinene oils; E. eugenioides a pinene-eucalyptol oil; E, macro- 

 rhyncha, E. capitellata and E. nigra a pinene-eucalyptol-phellan- 

 drene oil; and E. obliqua a phellandrene-piperitone oil. While 

 not departing greatly from the general form of the group, they 

 have, unlike the Corymbosas, been able to adapt themselves to very 

 varying climatic and physical conditions, as many of them occur 

 in cool, elevated situations; and this they seem to have been 

 able to accomplish, not by morphological change, but by virtue 

 of the oils they elaborate. The presence of phellandrene seems 

 to give, those possessing it, the power to flourish in a cool climate. 

 E. eugenioides is the most widely distributed member of the 

 group, being able to exist under very varying conditions of 

 climate and soil. It is very likely that it has been enabled to 

 do this by the help of its comparatively small cotyledons, and 

 its eucalyptol-pinene oil. 



Among the emarginate cotyledonary groups, one of the most 

 striking is (6), which might, for convenience, be called the 

 " Peppermint "-group, as many members contain piperitone, while 

 others contain pinene, phellandrene, and eucalyptol in varying 

 proportions. It is noteworthy that aromadendral, the charac- 

 teristic constituent of the "Boxes," is almost entirely absent. The 

 cotyledons in this group are characteristically quadrilateral and 

 the emargination is always slight and sometimes practically absent. 

 Another interesting point is that most of the members of this 

 group have reniform anthers, and many of them a characteristic 

 venation, which may be seen even in the primary leaves, the 

 lateral veins being very oblique, in fact almost parallel to the 

 midrib, and forming a looped arrangement with the intramarginal 

 vein, which is away from the edge. In the case of E. Eossii, 

 the evidence of the seedling is useful, as it explains the apparent 

 anomaly of the chemical composition, as this, while giving a 

 eucalyptol-pinene oil, and being classed chemically with species 

 which have generally parallel anthers and a different venation, 

 yet itself has reniform anthers, and a venation more character- 

 istic of the piperitone-group. I would also point out that, while 



