I\AU(iURAL ADDRESS. 
13 . 
coiRsidenitioiLS press ou the trained oUsen er, uiily one to he 
touched on here. Can the time approximately be determuied 
when the Diptrodon stamped in gigantic pace.s our plains, and 
when the Thylacoleon roai-ed in pursuit of other marsupials, mm 
exterminated ? 
One of the most remarkable of objects within the whole r-ange 
of biology is that of Symbiosis, the unexpectetlly wide extent of 
which through the empire of plants having lately been demon 
strated by Professor Beccaii — the hospes not proving detrimental 
or often not even injurious to the ho.st. Profe.ssor Frank very 
recently disco\ ered that fungus-growth of quite peculiar kind at 
the extreme ends of the root fibres in oaks, Ijeeches and trees 
allied to them, mediates the nutrition of them a.s a nece.ssity. 
Could all this be mei’ely casual ? The Azolla, noui-ishing a micro- 
scopic alge, is an example near to us, just as in othei' but simil.-ir 
respects the native evergreen beech. 
At the very time, when I left Europe, forty-two years ago. Count 
Sumin.ski discovered, to the surprise of nicUiy of us, the antherid- 
ous and archegonous organs on the minute prothallus t>f ferns ; 
but whether and how genetic relation exists between the j>rimordial 
and the .subsequently-developed sporangious organs on fern-fronds 
has never yet been traced or explained ; and this is all the moi-e 
mysterious as regards fern-trees, such as abound here, when years 
intervene between the production of the prothallus and that of 
the spore-bearing caselets. See fui'ther the vast significance of 
what, at first thought, may appear a mere trifling matter. 
A small fly i^Lestophories iceryae) was not long ago noticed as 
antagonistic to the coccid-insect Icerya purcfiasi, by the veiy 
observant Mr. Fraser Crawford, of Adelaide, though a closely 
allied fly, Lastophotius monophlebi, infests mainly, if not exclusively, 
another coccid, the Monophkbus crawfordi, as shown by Mr. F. 
A. A. Skuse, so that even in introducing the particular Diptere 
needed for subduing the Icerya very discx’iminative entomo- 
logy mu.st be brought to bear for coping with an evil of quite 
dreadful dimensions in Californian orchards, not to speak of what 
with the less powerful Coccinellides can be done. Thus the 
Agricultural Department of Washington found it necessary to 
send a professional entomologist purposely to Australia, in order 
that the Lestophones be e.stablished also on the other side of the 
Pacific Ocean, to restore thus far “the balance of nature;” just a.s 
in another I'emarkable instance the vines of the United States are 
largely reared in Europe and elsewhere now for their immunity 
to the Phylloxera vastatrlx, which fx*om America invaded other 
countries. Perhaps this parasite could likewise be subdued by 
other insects, such as would not attack the vines. If so, a question 
would be solved involving almost the whole interest of rural 
prospei'ity in many wide regions. So then a new special field is 
opened anywhere for entomologic observations, with a pro.spect 
held out of high substantial reward. 
