42 RicE: INTERNAL SORI OF PUCCINIA SORGHI 
in the corn. The production of spermatia and aecidia comes 
later in the pine stem, and Clinton believes that these sclerotia 
function as ‘‘storehouses to insure the penetration of the fungus 
through the vascular system of the leaf into the stem.”’ 
I first found internal teleutospores in a mature leaf on the 
under side of which a confluent line of teleutosori had broken the 
epidermis for a distance of approximately 2 cm. This strip of 
leaf was cut into pieces 3 mm. long and prepared for sectioning. 
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Fic. Internal teleutosorus in a storage cell of the midrib tissue of a 
corn leaf underlying an external sorus. Drawing made with camera lucida, 
400, 
The sections disclosed a succession of internal teleutosori, which 
apparently ran parallel with the external line of spores. In this 
midrib region of the mature leaf the bundles lie in the chloren- 
chyma close to the lower epidermis, while above them large 
thin-walled storage cells extend to the upper epidermis, giving 
the characteristic thickened central region of the corn leaf. 
The existe! sorus extends between two primary veins over 
two secondary veins. The close-set hyphal mass from which the 
teleutospores arise is of very limited depth above the bundles. 
Scarcely more than the epidermis seems to be destroyed. There 
