354 



When we pronounce a species a " disappearing " one, we do so because it seems 

 to be so ; it is a small species consisting usually of few individuals, and found on the 

 top or tops of hills, as if all the rest had been blown away, or had decayed away. This> 

 so far, is pure surmise, but facts in support we have none, so far as I know — we do but 

 interpret a vision, in the empirical way in which visions are usually interpreted. 



Dr. Willis's " Age and Area " conception is, at least, constructive. 



Mr. R. H. Cambage, in Journ. Roy. Soc, N.S.W., XLVII, p. 39, 1913, refers to 

 E. pulverulenta as follows : — 



*' Judging by results, it would seem to have been almost a necessity at some particular stage of 

 Eucalyptus development that some adjustment of leaf arrangement should have been made to conform 

 to some altered climatic condition, and ensure the further progress of the genus. The simplest method 

 for those species to adopt which had already developed petiolate leaves, was to gradually twist the leafstalk 

 and so change the position of the blade from horizontal to vertical. It is instructive to enquire into the 

 condition of one or two species which appear to have been unable to do this. 



One of the most interesting Eucalypts in this connection is E. pulverulenta (E. jndvigera), which is 

 growing in the Mountain region at Cox's Eiver, at Bathurst, and near Cooma. This tree appears to have 

 been unable to develop any lanceolate leaves at all, or to substitute the alternate for the juvenile opposite 

 arrangement, the whole of its foliage being either orbicular or broadly ovate, and, being sessile, the cordate 

 leaves remain clasping the stem at right angles, and therefore present their full surface to the sun. It is 

 now that we see the potentialities of the Eucalypt to adapt itself to its surroundings, and the method selected 

 in this instance has been to cover the leaves with a glaucous powder or vegetable wax, which reduces the 

 effect of the sun's rays and therefore lessens the evaporation, while it also serves to keep out the cold in 

 winter. It would seem, however, that this provision has not been so successful as the twisting of the leaf- 

 stalk, for this species is a weakling and rarely seems able to grow more than 20 feet high, and although in 

 the past it appears to have had an extensive range at least from Bathurst to Cooma, a distance of about 

 200 miles, it is not known in the intervening area, and is looked upon as rare in both localities. The available 

 evidence regarding this tree points to the conclusion that it is probably a vanishing species. 



E. cordata, of Tasmania, is a very similar little tree, and has adopted the vegetable wax instead of 

 the vertical leaf. The species is confined to Tasmania, and even there is not regarded as plentiful. It 

 seems not unlikely that in the near geological future both these species will have disappeared. 



In studying such problems of Age and Area, it is desirable that we should have 

 the Curving Boundaries of as many as possible of the species, and of this I have already 

 spoken. But this will take some time to carry out, and could hardly be complete (of 

 course, nothing is ever completed) until such time as the " Range " (or records of 

 distribution) given in this work have been Avell advanced. In spite of the fact that these 

 figures would be so economically and academically valuable, I cannot press the matter 

 at this time, in view of the fact that the New South Wales Government has been so 

 good to me in the matter of illustrations. 



Owing to the present state of my health, and bearing in mind that " time and 

 tide wait for no man," I have been compelled to add this to the many other phases of 

 Eucalyptus study that I must leave to younger and more active men. 



