Ward . — Recent Researches on the Parasitism of Fungi. 37 
Susceptible and Immune Varieties, and their Hybrids. 
A question of fundamental importance for our purposes is that of the 
immunity of certain forms of Wheat, and arising from this is the question, 
Can immunity be induced or propagated ? 
Mr. Biffen, working at our Experimental Farm, has done excellent 
service in recording the behaviour of certain races of Wheat, and in hy- 
bridizing and selecting them with great care and with an industry and 
perseverance not easily appreciated by those unacquainted with the kind of 
work involved. Much of his work has been directed to the testing of Mendel’s 
law, a question into which I do not however propose to enter here ; and this 
is the less necessary since he will himself bring this matter to your notice. 
Some time ago I asked Mr. Biffen to select for me grains of a sus- 
ceptible Wheat, of an immune Wheat, and of a cross between the two, and 
Mr. Evans and myself undertook to test them according to our own methods. 
The races Mr. Biffen was good enough to supply were A, Rivet Wheat, 
a form found to be almost immune, even when growing in the midst of 
Rusted Corn ; B, Red King, a very susceptible race, covered with Yellow 
Rust in the season ; and C, a crossed Wheat obtained by pollinating Rivet 
with Red King. 
This crossed form, on sowing and cropping, was found to be highly 
rusted the first year ; but in the second year yielded some plants which 
showed Rust and others which appeared to be practically immune, in the 
proportion of practically 3:1, whence Mr. Biffen concluded that suscepti- 
bility to Rust is a dominant and transferable character. This question 
does not, however, concern us. 
We sowed these several grains in separate pots of similar soil, similarly 
treated, and infected them in the ordinary way with spores from the same 
source. 
The susceptible form B (Red King) showed signs of pustules on the 
tenth day, and by the twelfth day was covered with pustules of Yellow Rust. 
The ‘ immune ’ form A on the tenth day showed what looked like 
very early stages of pustules, but these as a rule did not pass beyond 
the stage of pale flecks, and on the twelfth day showed a few spore-bearing 
pustules only. 
On this twelfth day the proportions of pustules on A and B respec- 
tively were as follows, counted on three leaves each : — 
A. Leaf 1 = 94 pustules. 
„ 2 = 7 pustules. 
,,3=2 pustules. 
B. Leaf 1 — | ]\/f an y hundreds of pustules : 
” — ( far too numerous to count. 
„ 3 = J 
