The Cereal Rust Problem— Does Eriksson’s Myco- 
plasma exist in Nature? 
By Gero, MASssEE, F.LS. 
THE idea that the vegetative condition of parasitic fungi exists in the 
tissues of certain host-plants, aud is transmitted from one generation to 
another, is not new. Berkeley (1), in discussing the subject, states as 
follows :—“ The mycelium of the cereal fungi is known to exist from the 
earliest period in corn, and is perfected only under favourable con- 
ditions.” Worthington G. Smith (2), in dealing with wheat rust, says: 
“They all prove that Puccinia is hereditary; that it exists in a finely 
attenuated state in seeds from diseased plants, and can be transmitted 
in a long interminable line from generation to generation.” (3), “ We, 
as well as many other observers, have shown that seeds apparently 
sound, will often, on germination, show disease in their seed-leaves ; 
such plants are saturated with the germs of disease from their earliest 
period of growth.” (4), Writing on the supposed hereditary nature of 
a disease affecting species of Dianthus, the same author states: “This 
case has a distinct bearing on the allied fungus of corn mildew, Puccinia 
gramims, which no one doubts is carried on from one generation to 
another in the seeds. This being the case, and nearly every grain of 
corn being probably saturated with the poisonous plasma of corn mil- 
dew, the statements regarding the production of mildew on corn from 
the contact of spores from a Barberry bush—the corn, it must be 
remembered, being almost invariably infested with hereditary disease 
—should be received with very great caution.” 
The above statements are not supported by experiments, but ad- 
vanced as the only apparently possible explanation of the repeated 
occurrence of disease in those cases where external means of inoculation 
were not evident. 
Quite recently Professor Jakob Eriksson (5), Director of the Ex- 
periment Station of the Royal Swedish Academy of Agriculture, has 
propounded a theory similar in substance to the ideas expressed by 
Berkeley and Smith, and bearing on the subject of rusts attacking 
cereals. The following quotations indicate the leading idea of the 
theory :— 
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