44 Ward. — Recent Researches on the Parasitism of Fungi. 
Phylogeny. 
It now remains to consider the bearing of some of the above pheno- 
mena on the phylogeny of the Uredineae. 
In 1881 ( 192 , p. 28) I recorded the fact that when uredospores of 
Hemileia vastatrix from Coffea are sown on Canthium campanulatum , 
another rubiaceous plant of Ceylon, the germ-tubes ‘ blocked up the 
stomata, sent their branches into the leaf, and commenced to form 
a normal mycelium in the intercellular passages of the leaf, as in coffee.’ 
I also put forward the view that the origin of leaf-disease on Coffee was 
due to the spores of Hemileia having passed from the native plant, 
Canthium , to the introduced one, Coffee. 
Although the words ‘ specialized parasitism,’ ‘ adaptive races,’ or 
‘biologic species’ were not used, it will, I think, be conceded that here 
was expressed the idea that a native jungle Fungus-parasite had adapted 
itself successfully to an alien host. 
But the idea of specialization of the parasite to the host was also 
present in De Bary’s mind, when he wrote ( 7 , p. 358, Engl, ed.) : ‘ We 
encounter on the other hand in these Fungi [parasites] a very long and 
varied series of phenomena of one-sided or reciprocal adaptation between 
the parasite and the living organism on which it feeds. . . . Every parasite 
species lives on certain host-species, and the limits within which it can 
choose its host are different in different species.’ 
And again ( 7 , p. 359) : ‘ These facts and gradations would lead us to 
expect that there must also be differences in the aggressive behaviour of 
a parasite to the different varieties and individuals of a host ; or, to express 
the matter in the converse way, in the predisposition of the individuals 
for the attacks of the parasite. In this direction also there are all possible 
gradations. 5 
Again ( 7 , p. 386), De Bary wrote: ‘The Fungi which are parasitic 
on plants naturally exhibit, within the limits of the chief phenomena of 
parasitic vegetation and its effects, ... a variety of special adaptations 
in respect of their choice of a host and their spreading in, upon, or along 
with it.’ 
But probably the clearest example illustrating De Bary’s attitude is 
the following : — 
In 1879 De Bary ( 12 ) worked out the heteroecism of Aecidium 
abietinum , and proved that Chrysomyxa Rhododendri is its alternate form ; 
but he found that at lower altitudes, although no Rhododendrons were 
present, the aecidium-form occurs, and showed that here the uredo-stage 
was Chrysomyxa Ledi. Although certain extremely fine distinctions exist 
between the two forms, which led De Bary to maintain them as species 
