302 DR. D. D. CUNNINGHAM ON MYCOIDEA PARASITICA, 
its host. On examining one of the affected plants, the injuries due to the presence of the 
parasite are visible at once (Pl. XLII. fig. 1). The leaves in varying number, according 
to the length of time which the plant has suffered, and dependent on the time of year and 
the nature of the weather, are seen to be irregularly eaten away at the margins, penetrated 
by circular patches of decay or of absolute loss of substance throughout their surfaces, 
or spotted with circular pustules of various sizes and various shades of colour, ranging 
from pale green to bright orange. On examining the pustules more closely, they are 
found to be slightly elevated, and of a more or less distinctly marked radiating structure ; 
and on looking at the margins of the holes and other deficiencies in the laminz of the 
leaves, they are generally found to be bounded by a distinct rim of like colour and 
strueture. Af certain seasons of the year numerous very minute, elevated, green spots 
and an abundanee of barely perceptible orange specks will also be encountered scattered 
over the surface of the leaves. The pustules and spots are almost invariably confined 
to the upper surfaces of the leaves; but in some rare instances they may be found on 
the inferior surfaces also. The latter phenomenon, however, is generally due to the 
extension of a pustule spreading round the margin from above. The size of the patches 
naturally varies greatly with the age of the plant causing them. On an average, patches 
which have not yet begun to die off in the centre do not exceed 5:0 to 6:25 millims. in 
diameter. The extent to which the leaves are affected varies greatly, but in advanced 
cases is sufficient very seriously to disfigure the plant. The very young leaves are seldom 
affected, owing, no doubt, in great part to the slow growth of the parasite. This is a 
matter of considerable economic importance in connexion with any form of parasitic 
growth affecting the Tea-plant. . 
On removing one of the pustules (which is easily done by the aid of a sharp knife), a 
brown discoloured patch of leaf-tissue is exposed, corresponding closely with the site of 
the pustule, and of various degrees of depth of colouring from a reddish brown to 
blackish. These discoloured patches in many cases penetrate the entire thickness of the 
leaf, and render the distribution of the Alga recognizable on the lower surface. In some 
instances the pustules are uniform in colour throughout, and end in a smoothly rounded 
margin; butin others the centre of the patch is pale, surrounded by a ring of deeper 
colour, or the margins, in place of being even, are more or less distinctly divided into a 
series of irregular radiating lobes. Even to the naked eye the appearance of the 
pustules varies much in different instances—in some being smooth and comparatively 
uniform, in others. covered with a crop of erect orange-coloured filaments, or variegated 
with minute orange points and specks. The structure of the patches always points to a 
peripheral growth from a central point; but their appearance varies greatly with the ` 
season of the year and the nature of the weather. | 
Commencing with the rains (the season when the vegetative growth of the plant is at 
a maximum), we find the following to be the anatomical features presented by fully 
developed specimens. They are then covered with a dense crop of erect filaments of 
various tints of orange and green. These filaments on close examination may be seen 
to proceed from beneath the epidermis of the host plant, and to arise from a flattened 
cushion of mediating filaments situated there, pp are net ane divided into a 
