tgit] PRITCHARD—DISSEMINATION OF PUCCINIA 189 
of the seed is filled with living rust would seem to depend chiefly 
on the presence of reserve food for the fungus and the capacity 
of the hyphae to grow through a few dead cells. The penetration 
of the dead tissue may and probably does offer some difficulty 
to the majority of the hyphae, but in some places only a single 
cell wall of the pericarp intervenes, which could scarcely be looked 
upon as an absolute obstruction. At any rate, an abundance 
of mycelium resembling rust was found in the scutellum close to 
the growing tissue, with apparently nothing to hinder its further 
progress in that direction. 
Whether after infection of the embryo in the manner suggested 
therust mycelium might grow with the plant and take on a virulent 
form at later stages, when it spreads to form pustules, is certainly 
an interesting possibility. Such a general systemic infection was 
assumed in ErRrksson’s mycoplasm theory, and there is some 
evidence in the general behavior of the rusts as noted above to 
suggest such a possibility. That such a palmelloid growth of 
fungal hyphae under peculiar conditions of nutrition is to be 
expected is abundantly shown by Racrgorskt’s interesting obser- 
vation on a palmella-like growth of Basidiobolus when placed in 
media rich in nitrogen. Further investigation of the infection of 
wheat by rust through the seed will be made when suitable material 
is obtained. 
Summary 
1. Puccinia graminis passed readily from wheat, Agropyron 
tenerum, A. repens, Hordeum jubatum, and Elymus triticoides 
to the barberry. 
2. Observed facts seem to oppose the theory that aecidiospores 
and uredospores are carried considerable distances by the wind. 
3. Uredo pustules of P. graminis appeared upon the experi- 
mental plot of winter wheat as early as upon grasses near the bar- 
berry bushes, and with one exception were generally present upon 
the spring wheat earlier than they appeared upon the grasses 
remote from the barberry. 
4. P. graminis does not appear to spread to the wheat fields 
by aid of the grasses. The few experiments made seem to show 
three distinct biological forms of this fungus: one for wheat, one 
