March i, 1882.] 
THE TROPICAL AGRICULTURIST. 
795 
the silk-worm disease, to destroy the invader by 
innoculating it with a parasitic fungus ; thus reversing 
the principle of all the previous applications of our 
knowledge of these organisms by treating them as 
allies instead of enemies. Unfortunately no experi- 
ments were made, and the subject was forgotten 
until last year, when Professor Hagen, of Harvard, 
published an account of his experiments on the de- 
struction of obnoxious insects by the application of the 
yeast fungus. He concluded that the yeast cells 
entered the body of the insect, there giving rise to 
fatal disease, and accordingly recommended the applic- 
ation of yeast to the phylloxera, Colorado beetle, &c. 
Such results as these, on the one hand confirming the 
old belief in the efficacy of yeast as a means of 
destroying greenhouse pests, and on the other at 
variance with all experience as to its mode of life, 
could not but stimulate inquiry. Tho subject was soon 
undertaken by a distinguished Russian biologist, 
Elias Metschnikoff, who has shown that the disease- 
producing fungus of Hagen was not the yeast itself, 
but was merely associated with it as an impurity. 
He has succeeded in cultivating several species of 
fungi parasitic upon insects, notably one which he 
terms "green muscardine " (Isaria destructor) and in 
tracing their entire life-history. By cultivating the 
green mnecardine apart from insects upon a suitable 
nutritive fluid, he has been able to obtain a consider- 
able quantity of spores, nnd thus feels justili.:d in 
recommending the cultivation of such fungi on a large 
scale, and the dissemination of the germs in places 
infested by insects. The subject is at present engaging 
considerable attention in France, and experiments are 
being made, of which we shall doubtless know the 
results in the course of next season. In the meantime 
it is impossible not to await with interest and hope 
this Application of a new method.— From an article on 
"Recent Science" in the November number of the " Mne- 
leenth Century." 
SUGAR GROWING IN MACK A V, NORTHERN 
QUEENSLAND. 
After careful inquiry and comparison of results, I 
am justified in setting down 1 ton 12 cwt. of sugar 
per acre as a fair average yield per aero from the 
canes all around. .With advantagi s such as exist, 
especially in tho climate of Mackay, this yield, 
though favourable as compared with other Queensland 
sugar districts, and highly profitable in itself, is below 
what might reasonably be expected, and probably 
much under what better cultivation and appliances 
will make it in course of time. Only in two instnnces 
have I observed manure to be applied. At Kouldt-n, 
Mr. Walker uses superphosphate of lime manufactured 
on the premises ; while Messrs. Hewitt and Co. apply 
stable manure on a part of their Pleystowe plantation. 
The crushing season begins in June and finishes 
about the middle of December, and during this time 
not more rain falls than is sufficient for nourishing 
the young canes— on an average about 17 inches. In 
some of the plantations these aro put in the ground 
almost as soon as the old canes aro cut down and the 
ground ploughed up. The cuttings are taken off near 
the top of the cane, and placed in a slanting position 
in the ground, in a way which leaves only a joint 
exposed above the surface, but in very dry weather 
even this is covered up— a work in which the kanakas 
have becomo export. There is another way in which 
the young canes are allowed to grow— that is, by 
rattoons, as it is called, the cane stumps being loft 
in tho ground, from which the next crop Borings np, 
tho oarth being ploughed up BO 08 to leave the stumps 
just covered, in general this proee-s is permitted to 
gO on for three years before the stamps are ploughed 
up for re-planting; it saves a great deal ..1 1 hour, 
and though the canes are not so vigorous as those 
which grow from plants, yet the stumps continue 
for three years to give a tolerably fair crop. In 
some cases they will yield a profitable crop for a 
longer period — even for five or six years ; but it is 
considered safer not to let the time exceed three years. 
It is remarkable to what a height the canes grow 
in well-cultivated and well-drained land. 1 have seen 
a crop standing in some places as high as 12 and even 
15 feet above tho ground ; and once, on tho ridges 
of the Pioneer, witnessed the singular spectacle of 
two men on horseback becoming invisible to each 
other at a short distance whiht riding among the 
canes. When the cultivation is good there appears 
to be no difference in this respect between tho rich 
level alluvial soil of the Pioneer and the dark soil 
on the hillsides ; both at the present time are equally 
prolific, but in a very wet season the hills would 
probably have the advantage. 
It is said that 11,000 tons of sugar will be the 
probable yield for the present year, but in comparison 
with the land unoccupied the district has barely been 
scratched, and it has been estimated on a fair calc- 
ulation, what may seem at the present stage an ex- 
aggeration, that no less than 250,000 tons of sugar 
per annum will be produced in the district when 
all the land is tilled with skill and care. Be that 
as it may, there is an immense tract of land yet 
open to the selector, but unfortunately, just as people 
are becoming anxious to take up land, the Govern- 
ment have withdrawn it from sale. When it is thrown 
open again, the rush for it will be enormous, judging 
by the number of inquiries which are made at the 
Mackay land office. The conditions are similar to 
those of New South Wales, and it is probable that 
in the Mackay district every selection will be contested 
for at auction. 
Cane-growing seems very catching ; nearly all who 
can embark in the enterprise ; sugar-growing and cane- 
planting are the principal topics of conversation in 
the town and in the country, and all the small 
farmers, of whom over 200 are said to have settled 
down, who formerly grew maize and tried their ban 1 
at cotton, have abandoned those industries for the 
more lucrative one of growing sugar-cane, which they 
dispose of to the millowners for about lis. per ton. 
— Australasian. 
THE CULTIVATION OF CASUARINAS. 
TO THE EDITOR OP THE MADRAS MAIL. 
Sin, — I must crave a small space in your paper 
to enable me to make a few remarks on the estimate 
framed by "B." for planting six acres of land with 
casuarina trees, as published in tho Eurasian and 
AiKjbi-lnilian Ailrora/e, and reproduced in your issue 
of the 20th July last. 
"B. " does not' provide for the expense of form- 
ing a fence or hedge for tho plantation to protect 
it from the ravages of cattle, &c. No plantation can 
thrive without a proper fence, and this should be the 
first tiling attended to. The American aloe or 
corkopilly plant, is well adapted for this purpose, but 
will require watering the first year, especially the 
latter plant. Both will repay their cost in tho third 
or fourth year, and be a sourco of revenue as long as 
the fence is kept up ; the only thing to bo taken 
into consideration is, the first outlay. " B. " also omits 
in his estimate tho assessment of tho land, and the 
interest on tho capital to bo laid out ; bnt I may 
mention heir, that (iowrnment grant waste land free 
ot assessment for twenty years for the planting of 
topes. 
The soil should bo of a looso sandy nature. These 
plants thrive brst on such soils, on tho sea coast, on 
i • claimed salt marshes, aud on tho slopes of the banks 
