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1 Funy, 1901.] QUEENSLAND AGRICULTURAL JOURNAL. 89 
Amongst such unpropitious influences are usually accounted those of soil and climate. 
These may be permanent or temporary in their operation. Amongst the temporary we 
may include excessive rainfall or dryness, and an unusual peverty of sunshine. 
The persistent uncongenial circumstances of growth alluded to, embrace, on the 
other hard, not only a meteorological element, but may also be connected with the 
physical and chemical nature of the soil. And they in turn may be regarded from 
two points of view—that of the requirements of the sugar-cane considered as a whole 
as a special division of the order of grasses, and that of the demands of the 
individual cane variety. In the latter case we may trace their effect when, as often 
happens, particular sugar-cane varieties, having a reputation for vigorous and healthy 
gro*th, fail to sustain it when transported to a new location, and possibly manifest 
the fact in being attacked by a discase-producing parasite of the nature of these 
already alluded to. It is by reason of this experience also that sugar experiment 
stations find it necessary to establish sub-stations where there are special soils and 
climate within the canegrowing districts coming within the scope of their operations. 
{It also points to the obligation that resides with every cane-farmer to test the 
capabilities of different sugar-cane varieties under the conditions of soil and climate 
that are exhibited by his immediate surroundings, availing himself of such expert 
assistance as he can enlist in estimating results. 
It may be further added, as a matter not generally recognised, that the dis- 
position to be victimised by parasitic life that a particular cane variety exhibits, 
either locally or throughont extensive districts, may possibly follow as the outcome of 
our own strenuous efforts in cultural procedures, or, on the other hand, be the result of 
inaction on our part. It is a very common persuasion, especially on the part of those 
that do not favour the bestowal—of course as a matter of principle—of much tillage 
upon cane lands, that any unfavourable modification that is displayed by the plant in 
process of growth is the expression of a state of soil poverty that has been arrived at. 
There are, however, grounds for concluding that instances, in which an explanation of 
the display of a tendency to disease is to be found in the concurrence of this circum- 
stance, are very much less numerous than is generally supposed, and that many 
apparent ones will readily disappear on resort to practice of ordinary farming proce- 
dures, other than those that consist in the application of manures and fertili ers. The 
visit to Bingera Plantation on the part of the delegates this afternoon should afford 
emphatic testimony of the truth of this proposition. 
With reference to the possible tendency of operations prompted by a desire to 
yssess a sugar cane of the anya quality, and in greatest amount, in promoting a 
ihepeeiiahyn to disease, allusion need only be made to what may be the outcome of 
efforts purposely directed towards securing a high sucrose yield as the exclusive end 
to be Eee without regard to the fact that this gain may accompany—-as a condi- 
tion of vital plant-equilibrium ~a proportionate deprivation of essentials—obscure, it 
may be, in their nature—on the possession of which the health and vigour of the plant 
may depend. 
How this undesirable result may be realised while in other respects an 
improved cane-plant is being acquired, will appear from what is to follow. 
Now, a very simple experiment teaches us that the primary and fundamental 
element of plant structure—~.c¢., the cell—is endowed with a cell-wall, whose elasticity, 
although variable within certain limits, is circumscribed. ‘This elasticity is occasioned 
by the necessity that arises as a feature in plant life for meeting the varying internal 
pressure of its contents—that is, the so-called cell-sap. Experiment will also indicate 
that when, as commonly happens, the plant becomes turgid or full of sap, the limit of 
this elasticity is practically reached —a statement that especially applies to the 
plant-cells that contain sugar in solution. 
Professor Pfeffer has shown in experiments with a single cell that when the 
dissolved sugar-forming part of its contents was increased from 1 per cent. to 6 per 
cent. in amount, this internal pressure correspondingly changed from a mercurial 
pressure of 53 cm. to 307 cm. Now, to meet this increasing cell-pressure, which is of 
course additional to that due to full plant turgidity, a cell-wall of greater resistance 
must be provided for, and there are grounds for concluding that this requirement 
can only be complied with by developing in the sugar-cane its mineral constituent that 
principally exists, and especially is this the case with lime in the cell-wall. 
Thus it would appear, the grower should aim in securing a cane with a high ash 
constituent as one of the concomitants that he endeavours by selection to associate in 
the cane with a high sucrose content, the mineral matter being principally inherent in 
the cell-wall, and the latter being resistant and strong in proportion to the extent in 
which this is present, 
