Srction D. 
BIOLOGY. 
1.—ON THE CONSTANCY OF SPECIFIC CHARACTERS OF 
THE GENUS EUCALYPTUS. 
By R. T. Baker, F.1L.S., Curator and Economic Botanist of the 
Technological Museum, Sydney, New South Wales. 
In this paper the author endeavours to show that much of the 
hitherto supposed variability of specific characters of our Euca- 
lyptus trees is the result of various artificial classifications 
applied to the species in the past, whereas, if classified on what 
appears to be a natural basis, the species possess very little, if 
any, variability, and retain in a marked degree individual cha- 
racters through their whole area of distribution. Each species 
is taken seriatim to prove a want of variation in its specific 
characters. This constancy is acounted for by the author 
on the geological age of this continent, for whilst other 
continents have undergone subsidences and upheavals, Australia 
has stood still or remained stationary, thus giving the plants 
enormous periods of time for differentiation, so that the “ missing 
links” naturally are wanting. Further, such a natural classifica- 
tion based on scientific data is of the greatest importance to the 
commercial community of Australia. For, as matters have stood 
in the past, under the old artificial régime it was quite possible 
(and actual specimens in the Technological Museum prove that 
such cases did occur) for a contractor, say, in bridges or railway 
sleepers, to supply an inferior timber under the botanical name 
specified by respective colonial Governments. [or instance, 
under the name of our mountain gum, Hucalyptus goniocalyz, 
F. vy. M., four distinct species are included, and of these only one 
is suitable for bridge decking; three are good for indoor and 
general work ; two are quite worthless, and all this is due to our 
having classified in the past our Eucalypts on what the author 
contends is an artificial basis, namely, morphological characters. 
By following a natural classification, that is, one founded on a 
long and intimate acquaintance with the trees in nature, their 
habits and places of growth, the form and qualities of their seed, 
the manner of their elevation, increase and reproduction, the 
peculiarities of their radication, their interior substances, the 
infinitely varied formation of their vascular system (by which 
the plant is not only enabled to circulate the juices necessary to 
