Ward. — Recent Researches on the Parasitism of Fungi . 33 
to call in another hypothesis, totally subversive of all the laboriously won 
doctrine of parasitism founded by De Bary. We may admit the possibility 
of other hypotheses-^-I would be the last to deny honour to him who 
proposes and tests such' — but we cannot accept such on negative founda- 
tions only. 
I venture to assert that Eriksson has omitted a precaution which might 
have saved him much trouble, viz. he has not compared the course of 
normal infection with the phenomena he describes. 
We had already worked out the chief points in the histology of 
Puccinia glumarum when Eriksson’s second paper (67) since my investiga- 
tion of the histology of P. dispersa was published in January, 1904, 
entitled ‘Ueber d. vegetative Leben d. Getreiderostpilze.’ This work was 
conjoint with Georg, Tischler, and deals with P. glumarum in Wheat. 
After a short and luminous introduction, showing how De Bary’s proof 
that Aecidium Berberidis belonged to P. graminis , Ae. Asperifolii on 
Anchusa belonged to P. Rubigo vera {P. straminis ), and Ae. Rhamni on R. 
catharticus and R. Frangula belonged to P. coronata , Eriksson states that 
this by no means ended the Wheat Rust controversy. 
True, De Bary’s results were in the main confirmed, especially as 
regards P. graminis. But all three Wheat Rusts have now yielded several 
other species, and have been shown to be each a multiple species. 
P. graminis is found to include two, P. Rubigo vera eight, and 
P. coronata two new forms which Eriksson regards as species. Of these 
only four species — P. graminis proper, P. dispersa , P. coronifera, and 
P. coronata — are known to be heteroecious, and of these only three form 
teleutospores which pass the winter before germinating, the teleutospores 
of P. dispersa germinating in the autumn of their ripening. Eriksson then 
goes on to repeat his opinion that it is impossible to explain the outbreaks 
of Rust in certain seasons by means of aecidiospores or of uredospores 
which have persisted through the winter ; and especially insists on his 
culture-experiments in the open, as driving to the conclusion that some 
internal source of infection exists. In other words, Eriksson holds fast to 
his mycoplasm hypothesis. 
But under what a different guise does the hypothesis now appear ! 
Hitherto we were asked to assume that the protoplasm of the Fungus and 
of the cell were amalgamated in an intracellular symbiosis, and that at 
certain periods this could be seen to be separating out the Fungus-mycelium 
as ‘corpuscules speciaux/ now shown to be the haustoria. 
Now we are told (67, PL 1, Fig. 2) that the vacuolated and granular 
contents of certain cells are probably the ‘ mycoplasm.’ Neither the 
figures nor the description give us any sufficient evidence for this assumption, 
however, and I see no reason for altering my opinion that Eriksson had 
here before him simply the intact protoplasmic contents of normal cells 
D 
