BY CUTHBERT HALL. 521 



afield, to leave the particular environment they aifect. The 

 group of the Eucalypts, that possesses the same type of cotyledon 

 and oil, viz., the Corymbosa-group, has, in some manner or other, 

 acquired the power of varying to some extent, by developing the 

 vertical, petiolate leaf at an early stage, and by varying the size 

 of the cotyledon. Chemically, they do not seem to have made 

 much progress, and have failed to develop eucalyptol, phellan- 

 drene, piperitone, or aromadendral, and so have been unable to 

 leave a sandstone-formation, or to penetrate to the high alpine 

 regions or dry interior. They prefer plenty of moisture, but can 

 resist heat, and so confine themselves to the warm, moist, tropical, 

 coastal areas. Their large foliaceous cotyledons could germinate 

 and maintain the young seedling, if plenty of moisture was 

 available, and served to protect the young radicle just pene- 

 trating into the soil. To make their advance, the Eucalypts 

 found it was necessary to reduce the size of the cotyledons, from 

 such relatively enormous ones as those of E . calophylla. This 

 was done in two ways : firstly, by a simple reduction in sizei 

 secondly, by cutting out portion of the cotyledon by the intro- 

 duction of emargination. The first method, we see well illustrated 

 in the Stringybarks. In E . Icevopinea, E . dextrojniiea, and E . 

 Wilkinsoiiiayia^ the oil is still a simple pinene one, and the 

 primary leaves, shortly petiolate, still have the glandular hairs, 

 but they have reduced the size of the cotyledons, and have 

 managed to ascend to the mountainous cooler areas. E . eugeni- 

 oides has reduced its cotyledons very greatly, and developed a 

 eucalyptol-pinene oil, and so has been able to penetrate all the 

 Eastern States, and, in a dwarf form, to exist on the high parts 

 of the Blue Mountains, and it can grow on soil of almost any 

 description. 



E. macrorhyncha and E . capitellata, also with fairlv reduced 

 cotyledons, and by the development of a pinene-eucalyptol-phell- 

 andrene oil, have been enabled to spread over the South-Eastern 

 States, and to work on to the mountains; while E. obliqua, by 

 the development of a phellandrene-piperitone oil, has been able 

 to establish itself over the mountains from the Queensland border 

 to Southern Tasmania. E. fastigata and E. regnans are pro- 



