i66 Effects ^^cidium esculentum on Acacia eburnea. 
slightly thickened sub-globose facetted part of the stalk that the 
florets are attached. The individual florets do not possess special 
stalklets. So much of the structure of the normal inflorescence it is 
necessary to detail in order to make the conditions in the diseased 
flowers intelligible. 
In the diseased flowers a ring of florets makes its appearance in 
the axils of the bracts near the middle of the stalk, that are normally 
sterile. The thickened end-parts of the stalk that are normally short 
and globose become elongated in such a manner as to transform the 
globular flower-head into a cylindric spike on which the florets in¬ 
stead of being crowded together are arranged at short intervals from 
each other. At the same time each of the florets developes a short 
special stalklet, and in place of all the florets opening simultaneously 
as they do in the normal flower-heads, those florets in the diseased 
spikes that are nearest to their apices are smaller in size and later 
of growth than those below them. It ought to be noticed that even 
in fruit there is no tendency in undiseased plants to elongation of 
the part of the stalk to which the pods are attached, and no disposi¬ 
tion on the part of the pods to ripen more quickly at the outside of 
the branch than in the centre. At the same time it has to be repeat¬ 
ed that it is entirely owing to special elongation of this part of the 
stalk in diseased flowers that the flower-head becomes changed from 
a ball into a spike, because the interval that in normal flower-stalks 
exists between the barren bracts and the flower-heads themselves 
still continues to exist, destitute of florets, between the circle of florets 
that appears abnormally in the axils of the bracts and the basal 
florets of the cylindric spike. This interval, which in undiseased 
flowers is 5—6 mm. long, measures 10 - 12 mm. in diseased ones. But 
the increase in length of this part is merely due to the general 
hypertrophy produced by the disease, and it is not its size but its 
existence at all in the diseased flower that is of interest. 
Expressed in technical teratological language the conditions in^ 
duced by the disease are .- — Increase in the size of the parts affected 
by general hypertrophy, with some alteration of shape by distortion 
combined with conversion of florets from sessile to pedicellate by 
elongation, conversion of a capitate inflorescence into a spike by 
apostasis, change of a simultaneous and therefore at least sub-definite 
88 
