Ward —Recent Researches on the Parasitism of Fungi. 49 
beobachtete ich es an Polygonatum- Pflanzen, die mit den Sporidien von 
Puccinia Conv altar iae-Digraphidis besat worden waren.’ 
I have facts which go to show that infeetion-hyphae thus arrested 
in development — whether owing to the high temperature prevailing at the 
time or to reactions of the host-cells and independent of temperature — are 
not killed, but may lie dormant, and may later on resume their growth . 
If we can show that such inhibition and arrest of growth can be prolonged 
for more than a few days, the persistence of such dormant mycelia might 
explain a good deal. But it would not go to strengthen the mycoplasm 
hypothesis. But there is another point. 
I have already stated (p. 13 ) that several observers agree that 
uredospores can live and remain capable of germination for long periods. 
I found those of P. dispersa retained their germinating power for sixty-one 
days ( 191 , 1903 , p. 138 ), and only brought the experiments to a close from 
lack of material. Miss Gibson has found uredospores of Chrysanthemum 
Rust germinate after keeping for ninety-four days, and has not yet reached 
the limit. Magnus ( 108 , p. 18 ) found the uredo of P. Caricis persisted 
through the winter on the plant ; Schroter found ( 156 , p. 3 ) the same 
thing with a Puccinia on Luzula ; and Barclay (2, p. £27) states that the 
uredo of P. coronata was found in winter ; while Lagerheim found that 
of P. Poccrum on Poa after the melting of the snow ( 102 , p. 124). I myself 
found germinable uredospores of P. dispersa during every month of the 
year 1 901-2, even in February and March ( 191 , p. 132), and other cases 
are cited on pp. 13 and 14. 
Conclusion, 
Seeing that uredospores can be found nearly or quite all the year 
round ; that they can be developed on odd tufts of grass here and there 
during the winter ; and that they will retain their germinating power for 
two to three months — perhaps longer ; that, further, specialized forms are 
not absolutely adapted to their hosts, but can occasionally infect races of 
Wheat, &c., which normally prove immune, or can pass from one hitherto 
excluded variety to another by means of 6 bridging ’ species, where is the 
necessity of the mycoplasm hypothesis ? 
Moreover, it has been clearly shown — and is now conceded — that the 
so-called ‘ special corpuscules 5 supposed to be the { mycoplasm 5 were 
merely haustoria ; and I have traced all the phases of infection by means 
of sections at all stages shown in the field, and by means of similar 
sections at intervals of one, two, three to eight, or ten days after inoculation. 
It has been shown that pure cultures of the Uredine give no evidence 
which lends the slightest support to the mycoplasm hypothesis ; and all 
the evidence obtained from the study of starvation phenomena is equally 
non-supporting. 
E 
