in the Bromes and their Brown Rust . 237 
of shape, size, colour or other, morphological characters, but 
differing in some capacity of reaction towards another host. 
It is, of course, a matter of pure hypothesis as to whether 
these intangible physiological differences will ever bring about 
morphological changes of so obvious and relatively permanent 
a nature that we should then recognize the differences as 
specific. As will be seen, also, there is danger of some con- 
fusion of ideas as regards adaptation and variation on the 
part of the fungus, and we must not lose sight of possible 
reactions of the nature of resistance or predisposition on the 
part of the host. 
So impressed was Eriksson with the significance of his 
share of the foregoing facts, and especially with certain 
difficulties met with in explaining the sudden and serious 
epidemic outbreaks of rust which occasionally occur, that he 
committed himself in 1897 to the remarkable hypothesis that 
at certain seasons the rust-fungus attacks the grass, e. g. 
wheat, and passes the protoplasm of its spores into the 
embryo, or some other part of the plant, where it mingles 
with the protoplasm of the host, and lives a common life of 
symbiosis with the living cell-contents, to break out suddenly 
at a favourable opportunity as rust. This supposed symbiotic 
form merged in the protoplasm of the host he termed 
My coplasm. This is not the place to enlarge upon the fact, 
which all who have followed his splendid investigations into 
wheat-rust must admit, that anything on this question coming 
from Eriksson is entitled to respectful consideration ; but it 
does appear pertinent here to say that the question may be 
raised, whether Eriksson had not done better to retain the 
first term which gave the title 1 to his communication on this 
subject ; for while there is plenty of evidence that the mycelium 
can remain dormant at certain times and under certain con- 
ditions in leaves unsuitable for its further development, there 
is little or none so far as I can find to support his hypothesis 
of this mysterious Mycoplasm. 
1 Vie latente et plasmatique de certaines Uredinees. Compt. Rend., 1897, 
P* 475 - 
