18B 
Jan. 81, 1911. The Queensland Naturalist. 
producing profound changes in the leaf-tissue, the loose 
elongate cells of the mesophyll dividing transversely and 
having produced — through stimulation due to the presence 
of the parasite — an abundance of special tissue to iVirni 
the basis of the large weal-like bodies referred to. in 
this case, moreover, the parasitic organism itself occupies 
cavities in the new tissue, each lined with a special sub- 
stance of fungu-s origin (stroma), and containing trans- 
parent-walled sacks (asci), each holding about eight oval, 
pinkish-brown, continuous spores. These cavities (or peri- 
thecia) corresponding in position to the pustules on the 
leaf-swellings, gradually develop thick black walls and 
burst through the surface, apparently however not liberating 
the spores that they contain until the decay of the leaf,- 
in connection with which they occur. This is an instance 
of parasitism where marked alteration of the host’s tissue 
results from its occurrence. 
5. Gall-producing Fungus of Acacia (Uromycladium 
Tepperianum — Uredinece), Cunningham’s Acacia {A. cun- 
ninghamii) is the plant-host in this instance, and it majr 
be remarked that, notwithstanding the organism falls 
within the same group as the Leaf Rust Fungus of Acacia 
already mentioned, and in fact was originally described 
by Saccardo under the generic name Vromyces, the ejects 
produced on their victims by the two parasites are strongly^ 
dissimilar. Here we have an immense, chocolate-brown,, 
irregularly contorted or distorted mass composed of new 
tissue {Hyperplasy), measuring 3 to 4 inches across, forming 
a most conspicuous object on the branch that supports 
it, instead of the speck-like pustules on the green phyllodes,. 
as with Vromyces phyllodiorum attack. In fact the Uro- 
mycladkim gall is formed by the perennial spawn threads 
(mycelium) of the parasite continually irritating the growing 
cells and effecting their multiplication, whilst the powdery,, 
rusty, brown exterior marks the continuous formation 
in a thin but compact layer of reproductive organs (teleuto 
spores), large, beautifully fluted and striated spores, in 
clusters of three each on solitary stalks. This parasite 
has moreover some economic importance, since the diversion 
of the nutrient fluids into the galls often kills the branches 
of the tree or bush on which they occur. Moreover, it 
does not confine its attacks to one Acacia species.* 
* Note. —For a full account of the genus Uromycladium, reference 
should be made to D. McAlpine’s “ A New Genus of Uredineae Uromy- 
cladium,” Annales Mycologici, III., &c., 1905, 32‘2— 323, pi. vi~ix. 
