Ward . — Recent Researches on the Parasitism of Fungi. 19 
The Bromes and their Brown Rust. 
In 1902 I published the results (191 and 199) of my first experiments 
with the Bromes and their Rust-Fungus, P. dispersa , f. sp. bromina , and 
have continued these during the intervening years. 
My point of view involved some generalizations based on previous 
experience — for I may be allowed to say that the Uredineae and their 
parasitism is an old study of mine. 
In the first place, it has always appeared to me that we are too apt to 
overlook the behaviour of the host in its relation to the Fungus, whereas 
the physiological condition of the host is always a factor of prime im- 
portance. 
Secondly, the real meaning of infection can never be thoroughly under- 
stood merely from culture-experiments in the open : it will be necessary to 
examine not only the behaviour of the Fungus in detail, and the reactions of 
the host-plant to the Fungus, but also the effects of the environment on both. 
It was an obvious idea that in order to attack a task of this kind 
properly, care must be taken that both the Fungus employed and the hosts 
to be infected by it must be definite as regards species, and pure as 
regards origin. Consequently, my first object was to work with one species 
of Puccinia only, and to confine the infections to one genus of plants. 
I chose Puccinia dispersa , the Brown Rust of Grasses, and the genus Bromus , 
on which one form of this rust is common, viz. the specialized form, f. sp. 
bromina. 
There is still some doubt among authorities as to whether this Fungus, 
growing on the Bromes, and, as we shall see, very closely specialized in 
that group, should or should not be accorded specific rank. Eriksson has 
sharply criticized me for continuing to name it P. dispersa , and his 
contention that it should be regarded as a species (P. bromina ) is perhaps 
strengthened by F. Muller’s discovery that it is heteroecious on Sym- 
phytum, 
But, while according all due respect to Eriksson’s opinion, I maintain 
that a species must be capable of morphological distinction before it can 
be accepted as good. 
Meanwhile this Puccinia (formerly included in P. striaeformis , 
Westend. ; P . straminis , Fuck ; P. Rubigo-vera , DC.) was first included 
in P. dispersa , Erikss., and then separated as P. dispersa, f. sp. Bromi, and, 
later, separated still further as a species, P. bromina , Erikss. ; while 
Klebahn, accepting Muller’s name, has it as P. Symphyti-Bromorum , 
F. Mull. 
Such are the complexities daily being perpetrated in synonomy ; and 
I hold them to be unnecessary until we discover morphological differences 
in this form sufficient to distinguish it from P. dispersa. 
