On the vegetative life of some Uredineae 1 . 
BY 
JAKOB ERIKSSON, Ph.D., 
Professor at the Royal Agricultural Academy , Stockholm. 
I. Introductory Remarks. 
I N the middle of i860 Anton De Bary succeeded in proving by 
experiments the power of some corn-rust Fungi to live in different 
forms on two or more distinct hosts, that is to say, their so-called 
Heteroecism. 
At first, and for some time, there was no doubt that the question of 
the corn-rust had been solved through this discovery. The aecidium- 
forms on Berber is, Rhamnus , and Anchusa were considered to be indis- 
pensable generations of Puccinia graminis, P. coronata , and P. rubigo-vera . 
Then, this being the case, one must get rid of the corn-rust by rooting out 
from the neighbourhood of the cornfields as radically as possible the plants 
attacked by the aecidia. In several countries of Europe and America they 
have begun a war of eradication against the plants mentioned above, 
especially against the barberry bush. 
It is true that many researches during the following decennia have 
confirmed the results of De Bary in essential points. Repeatedly it has 
been shown that aecidiospores of barberry, &c., if sown on the young 
leaves of corn, infect them and produce the uredo and then the puccinia 
on them. Conversely, the sporidia of the puccinia, if sown on the young 
leaves of barberry, &c., infect them and produce the spermogonia, and then 
the aecidia on them. 
But at the same time it has become more and more manifest that the 
process of development of the corn-rust diseases cannot be quite as simple 
as it was considered at first. 
1 Read before the Botanical Section of the British Association, Cambridge, August 22, 1904. — 
Conf. J. Eriksson, SurVappareil vigttatif de la rouille jaune des cir tales, Compt. Rend., 1903, p. 578. 
Vber das vegetative Leben der Getr eider ostpihe , I, Kgl. Sv. Vet.-Ak. Handl., 1904, Bd. xxxvii, Nr. 6. 
Nouvelles recherches sur Vappareil vtgttatif de certaines urtdintes , Compt. Rend., 1904, p. 85. Vber 
das vegetative Leben der Getreiderostpilze, II— III, Kgl. Sv. Vet.-Ak. Handl., 1904, Bd. xxxviii, Nr. 3. 
[Annals of Botany, Vol. XIX. No. LXXIII. January, 1905.] 
