98 REPORTS ON THE STATE OF SCIENCE.— 1915. ^ ; ' 



to the genus but that there are conesponding chemical characters 

 which are just as pronounced and sometimes even more constant than 

 the botanical. There is also reason to believe that such botanical and 

 chemical features have been evolved coincidently, in a more or less 

 uniform manner. 



Eucalyptus trees take many forms of growth and their botanical 

 features and chemical characters are often most diverse. They are 

 roughly divided vernacularly into groups and sub-groups ; the names 

 that are given are largely indicative of certain physical features. 

 Incidentally, it may be mentioned that scientific study has shown that 

 these vernacular groupings hold good in a remarkable manner; thus 

 the terms 'Bloodwood,' 'Peppermint,' 'Ironbark,' ' Stringybark,' 

 'Ash,' 'Box,' 'Gum,' representative, more or less, of groups, ai-e 

 applied to species having similar and comparatively constant features 

 throughout the whole area of disti'ibution. Other common names, 

 however, are representative only of particular species, e.g., 'Tallow- 

 wood,' 'Spotted Gum,' 'Blue Gum,' 'Red Gum,' &c. Although 

 intended to be distinctive, these are often only so over very restricted 

 areas ; the ' Blue Gum ' of Tasmania, for instance, is quite distinct from 

 the ' Blue Gum ' of Sydney and the ' Eed Gum ' of one locality is often 

 a species different from that called ' Red Gum ' in another district. As 

 an illustration of the way in which the main groups are arranged into 

 sub-groups, the ' Box ' group may be mentioned, which is divided 

 vernacularly into ' Red Box,' ' Grey Box,' ' Yellow Box,' &c. ; similarly 

 the ' Stringybark ' group is subdivided intoi ' Red Stringybark,' ' White 

 Stringybark,' &c. , the 'Ironbark' group into 'White Ironbark,' 

 ' Broad-leaved Ironbark. ' It will be obvious that the features of the 

 several species must be of a fairly constant nature, otherwise local 

 nomenclature would be of little use for industrial purposes. 



The value of well-marked physical features as an aid to a general 

 classification becomes evident on studying the botanical features of the 

 several species and groups; it is then seen that there is a striking 

 similarity between the several species of the more well-defined groups, 

 the seedling leaves, the anthers, the leaf -venation, all agreeing closely 

 within each group. None the less, although these are often distinctive, 

 thei'e is no well-marked line of separation dividing one group from 

 another ; it would seem that there has been uniform development from 

 one species to another throughout the genus, although gaps in the order 

 of agreement naturally occur here and there. It is suggested that the 

 more obvious botanical changes have been mainly due to slow evo- 

 lutionarj' development under the influence of environment, soil and 

 climate. Altitude, climate and soil seem to be the chief controlling 

 factors governing the geographical range of most of the species (1). The 

 adaptation of the various species is traceable, largely, to influences of 

 chemical constituents, which under natural conditions, where the 

 struggle for existence is exerted to the fullest, govern the establishment 

 of a species in its earliest stages. It does not seem possible for certain 

 species to grow satisfactonly in soil not congenial to their requirements. 

 Eucalyptus trees vary considerably in size, from the small shrubby 

 forms known as ' Mallees ' to those representing some of the largest 

 trees in the world (-). 



