56 Eriksson . — On the vegetative life of some Uredineae . 
Now we know that we have to count with twelve instead of three 
species of corn-rust Fungi. P. graminis is divided into two species, P. coro- 
nata into two, and P. rubigo-vera into eight. Among these twelve species 
we find only four, P. graminis sens, strict., P. coronifera , P. coronata , and 
P. dispersa , which are heteroecious, and among these four species only the 
three first-mentioned have their teleutospores germinating in the spring 
after they are developed. The teleutospores of P. dispersa already ger- 
minate in the same autumn as they are developed. 
Consequently we can explain the reappearing of the corn-rust in the 
following summer, in accordance with the principles of De Bary, only so far 
as concerns the three species with the teleutospores lasting the winter. In 
the case of P. dispersa that is impossible, because the aecidia on the 
Anchusa , like the Anchusa itself, end their lives before winter sets in. 
Further, we must notice that Berberis , Rhamnus, and Anchusa do not 
at all occur so commonly as to explain the ubiquity of the corn-rust. In 
consequence it has become more difficult now than formerly to explain 
a rust-epidemic on our cornfields in a satisfactory manner. 
Finally, I wish to observe that very numerous detailed studies executed 
in the open air during the last decennium, as well as many isolated cultures 
during the same time, have indicated the great probability of there existing 
an internal source of disease in the corn-plant itself, these internal germs 
being inherited from the parent plant. 
In several works 1 I have submitted the hypothesis that the rust-fungus 
in the corn-varieties, extremely susceptible to rust, must live for a long 
time a latent symbiotic life in the cells of the plant itself — this symbiosis 
being called my coplasm — and that only a short time before the eruption of 
the rust-pustules, when external conditions are favourable, it enters upon 
a visible state, assuming the form of a mycelium. 
The mycoplasm hypothesis has been contested by many authors in 
several countries. However, through the criticisms presented I am not 
convinced of the error of the hypothesis. On the contrary I will now 
demonstrate some new investigations which appear to afford a good support 
to the theory already suggested. 
Since the summer of 1902 I have been working at a cytological 
research on the vegetative life of the corn-rust Fungi. In this work I was 
effectively supported in the summer of 1902 and 1903 by Dr. George 
Tischler from Heidelberg. 
Material of leaves, straws and ears of several corn-varieties, collected 
in several seasons and in varying stages of development, was fixed for the 
1 J. Eriksson, Vie latente et plasmatique de certaines urddindes , Compt. Rend., 1897, p. 475. 
Der heutige Stand der G etr eider ostf rage , Ber. d. Deutsch. Bot. Ges., Bd. xv, 1897. SurVorigine et 
la propagation de la rouille des c dr dales par la sentence , Ann. d. Sc. Nat., Bot., ser. 8, t. 14-15, 
1 901-2. The Researches of Professor H. Marshall Ward on the Brown Rust on the Bromus and 
the Mycoplasm Hypothesis , Ark. f. Botanik, Stockholm, 1903., s. 139. 
