Went . — Notes on Sugar-cane Diseases. 589 
a yeast-form, but as I have not been able to get this in more 
cases, and as I have never seen under the microscope that 
conidia of Colletotrichum falcatum form yeast-cells, I think 
it is probable that these yeast-cells were an impurity which 
had somehow found its way into the cultures. 
II. Pineapple-Disease ( Thietaviopsis cthaceticus). 
In most cases this disease only attacks cuttings, though it 
may be found in the stems of half-grown or full-grown cane too, 
if these are damaged ; but this last mode of occurrence of the 
disease is very rare. 
Diseased cuttings are blackish on the cut surface ; on 
dividing them longitudinally the interior shows a red or crimson 
colour, if they are only slightly diseased, whereas the more 
serious symptoms are a black colour in the centre of the 
crimson-coloured part. When diseased cuttings are planted, 
or when the disease breaks out after the cuttings have been 
planted, the buds do not sprout, or die shortly after having 
sprouted. Very characteristic is the odour of diseased canes, 
as soon as they are cut ; it reminds one of different fruits, 
especially pineapples (hence the name). 
In examining the diseased tissue under the microscope, it 
will be seen that the red colour is occasioned by dead cells, 
of which the cell-walls have taken this colour ; in the interior 
of these cells is to be found the colourless mycelium of 
a fungus. The black colour is occasioned by the conidia 
of this same mould. 
It is very easy to cultivate the fungus ; these conidia soon 
germinate in a drop of any nutrient solution ; some stages 
of germinating conidia are represented in Fig. 12. 
Cultures of the fungus remain snowy-white so long as only 
vegetative mycelium is developed ; but very soon (twelve to 
twenty-four hours) afterwards the colour grows darker, 
somewhat olive-green or dark green (between Nos. 34 
and 39 of Saccardo), in consequence of the formation 
of conidia. These conidia exist in two kinds, which I call 
