16 
ROYAL HOBTICtJLTUIlAL SOCIETY. 
cessary cause of the above-mentioned indications of disease, which 
have been generally recognized for the last three years. I have 
had occasion to observe plantations much affected with Scale which 
have yielded good sugar, and in which not a single cane exhibited 
the disease in question. 'No other insect, in spite of repeated 
observations, has been discovered to which the malady could be 
attributed. 
A ruddy tint in the wood- and cambium-tissue in the neighbour- 
hood of the joints is an infallible sign of the malady. As the dis- 
ease advances, this colour permeates these tissues through the 
whole of the stem, whereas the parenchyma at first retains its 
natural transparency. When the disease is fully established, a 
thick yellow substance flows from these vessels, which hardens 
when exposed to the air, but dissolves in water, and under high 
powers of the microscope exhibits a granular structure. Minute 
cells appear, either collected in irregular heaps or disposed in 
moniliform rows, which, when placed in a solution of sugar, are 
developed in the course of from six to eight days into a beautiful 
filiform Alga *. To assure myself that this did not arise from 
spores derived from the air, I placed repeatedly, and in different 
places, a solution of sugar under a bell-glass, but never obtained 
the same Alga, while it always occurred in the yellow substance 
placed in a similar solution. In confirmation of its deleterious 
influence, I have found the Alga itself in diseased canes ; I have 
observed also its infusorial spores and their fermentative action in 
the manufacture of sugar. Sporangia sown on the sheaths of the 
cane generate the Alga in the tissues in from one to two days. 
Hydrogen and carbonic acid are generated with such energy and 
speed in the juice of the cane when placed in the caldron and 
acted on by the fermentation produced by the sporangia, especi- 
ally at the commencement of the development of heat, that the 
scum runs over the brim of the caldron in great quantities. The 
organic acids developed by fermentation in the further process of 
boiling effect a change into uncrystallizable sugar. The extremely 
small quantity of crystallizable sugar (it being premised that the 
disease has not advanced too far) is very dark and of a very indif- 
ferent quality. In the moulds from which the molasses have run, 
where, as is the custom here, a mixture of clay is used for refining, 
the fermentation recommences so energetically that the melted 
sugar flows over the margin of the mould. 
* Or, rather, Fungus j no Alga is ever developed under such eireumslances*— 
M.J. B. 
