EXPLANATION OF PLATE I. 
Fig. 1.—An onion plant which has suffered severely from the disease, 
showing the withered bent-down leaves and the long stalk. 
Fig. 2.—Surface view of the epidermis of an onion leaf with a 
fungus stem protruding through a stoma. Magnified about 200 
diameters. EP., epidermal cells; sP., spores; ST., stem of fungus 
(P. Schleideniana) ; sto., stomata. 
Fig. 3.—-Section through an onion leaf, showing cells of the leaf and 
the air spaces between them in which the root-like processes of the 
fungus grow. The section passes through a stoma, and shows two 
stems of the fungus passing into the air and bearing spores ( x 200) ; 
CC., chlorophyll cells, which give the leaf its green colour; DC., deeper 
cells not containing chlorophyll; EP., epidermal cells ; 1P., air passages 
between the cells ; SP., spores; ST., stem of the fungus; sTO., stomata ; 
TP., tubular processes ramifying in the air passages. 

