BY CUTHBERT HALL. 525 



Eucalypts," which was stated, at the time, by the authors to be 

 tentative. This examination of the seedlings strongly confirms 

 the main principles laid down, however. The ancestor of the 

 Corymbosas had comparatively large, entire, reniform cotyledons. 

 In E. calophylla, we see the extreme in size. To meet Australian 

 conditions, it was necessary to reduce the size, and this we see 

 first in the Corymbosas themselves, till we get the smaller coty- 

 ledons of E. ti^achyphloia. The Stringybarks appear to have 

 arisen as an offshoot of the Corymbosas, and have smaller coty- 

 ledons of similar type, and hair}'^, primary leaves, but have 

 developed reniform anthers. At the extreme end of this group, 

 E. regnans, with smoother leaves, has lost its "stringy" bark, 

 while E.fastigata, its very near relative, retains it. It is difficult 

 to say where emargination first arose. Traces of it are seen in 

 E. intermedia; and E. Planchoniana and E. maryinata, with 

 large, emarginate cotyledons, may be descendants of the earlier 

 examples of it. The former seems to be a transition-form to the 

 great group of Peppermints, and their allies. It has cotyledons 

 and primary leaves of the same type, but parallel anthers of the 

 corymbosa-type. Chemically, it resembles E. pilularis and others 

 of that group. The seedling of E. SmitJiii confirms its probable 

 mixed ancestry. The cotyledons and oil are of the glohulus- 

 type, and the primary leaves and anthers betoken a relationship 

 to E. atnygdalina. If ever a species has claims to a hybrid 

 ancestor, it has. 



In the emarginate globulus-type, the rule has been to make a 

 general reduction in size of the cotyledon. But in Western 

 Australia, to combat the specially dry conditions there, a special 

 type of cotyledon was evolved, of a deeply bifid form, and this 

 has spread along the southern coast to Eastern Australia, and 

 even up into the far western parts of Queensland. Accompany- 

 ing these changes in the cotyledons, there has been a change in 

 the essential oils. The corymbosa-type is associated with a pinene 

 oil without eucalyptol. That of the Peppermint-group is asso- 

 ciated with eucalyptol, phellandrene, and piperitone in varying 

 proportions. The globnlus-type of cotyledon is mainly associated 

 with a eucalyptol-pinene oil, and in its reduced form aromaden- 



