Jan. 1905.] | BOTANICAL SOCIETY OF EDINBURGH. 63 
PERICLES JOANNIDES, Esq., and Dr. R. Stewarr Mac- 
DouGALL contributed a note on Puceinia graminis. From 
his own observations on the disease in Egypt, Mr. Joannides 
gave several instances of the continued existence of the 
Puccinia during several years without the usual presence in 
the life-cycle of the teleutospore condition and consequent 
eecidium stage on the barberry. 
NOTES ON PUCCINIA GRAMINIS. By P. JOANNIDES. 
The rust of wheat—this well known and much dreaded 
pest, so destructive to the wheat crops of all the wheat- 
growing countries of the world—is caused by the parasitic 
fungus Puccinia graminis, which belongs to the order Uredinee. 
Of this family almost 2000 species have been described ; they 
are parasitic between the cells of the host. This fungus, like 
some others of its allies, is extremely interesting as affording 
an example of hetercecism, 7.c. it appears in one or more forms 
on one host, and deserting this host it appears in other forms 
on another and not related host. The two hosts are the 
wheat-plant and the barberry. 
The vegetative portion of the fungus is not visible to the 
naked eye— the mycelium ramifying through the intercellular 
spaces of the affected parts of the host plant, and also 
sending out haustoria into the substance of the cells. When 
maturity is reached, spores are produced, which, bursting 
through the epidermis of the host, give rise to the rusty 
appearance so characteristic of these fungi. 
This fungus produces several kinds of spores. 
The teleutospores produced on wheat late in the summer 
are invested with a thick wall, and are dormant spores serving 
to tide the fungus over the winter. When weather permits, 
early in the spring these spores germinate, forming what is 
often called a promycelium, which gives rise to sporidia. It 
is believed that these sporidia cannot infect a wheat-plant, 
but that the barberry is necessary as the next host. 
The mycelium in the barberry gives rise to two sets of 
structures—spermogonia on the upper surface and ecidia on 
the lower. The flask-shaped bodies on the upper surface of 
the barberry leaf produce a great number of so-called 
