Feb. 17,1923 
Parasitic Fungi Internal of Seed Corn 
519 
A brief discussion of the morphology of com may help in explaining 
the exact nature of this internal parasitism. The kernel, seed, or corn 
to which it is commonly referred is a ripened fruit or caryopsis. It con¬ 
sists of a mature ovary with all its adnate parts. The kernel is estab¬ 
lished in a “fruit cup” formed by six fruit envelopes. According to 
Winton (59) this cup consists of— 
three glumes—a flowering glume, a palet, and another palet belonging originally to 
a rudimentary blossom. 
The cap of the kernel consists of a dried tissue, nonfunctioning at matu¬ 
rity. The peripheral cells of the cap are continuous with those of the 
pericarp. They are approximate to the integuments on line with the 
base of the scutellum. The integuments curve in towards the dorsal 
end of the scutellum. The inner structure of the cap consists of thick- 
walled cells and several vascular strands. This cap if partly cut or 
broken off exposes a small cavity over the dorsal extremity of the scu¬ 
tellum. There is also observed a brown covering adhering to the lower 
dorsal end of the scutellum. The cavity varies in size, and the covering 
over the scutellum is light brown to black, according to variety. 
The vascular bundles in the cob above the butt have a peripheral dis¬ 
tribution, so that the center or pith is made up of only parenchyma 
cells. The attachment of a pair of ovaries converge to a common base 
in relation to the vascular system. The ovaries are in direct relation to 
several bundles which gradually converge into several strands near the 
base of each ovary. This relation in a young cob can be seen with a 
hand lens. It is mentioned briefly here since it explains the path of 
infection if it occurs through the vascular system. If such infection 
resulted it would seem that the pairs of kernels would be equally infected. 
The four fungi mentioned have been found commonly established with¬ 
in kernels which show no symptoms of disease. It was further impossible 
in many cases to correlate any of the various symptoms of the butts of 
ears with such infection. The mycelium is found extensively developed 
in this cavity. In Fusarium moniliforme and Cephalosporium sacchari 
abundant internal spore production is found (PI, 7, A). This can easily 
be determined with a hand lens or with the low-power objective of the 
microscope. In some instances where the fungus has progressed to the 
tissue of the embryo in kernels showing no external symptoms, a free¬ 
hand longitudinal section will show a discoloration of the embryo as well 
as fungus development in the cavity around the radicle and the plumule 
(PI. 8 A, B). The development of the fungus from the cap into the 
germ and endosperm appears to be restricted by the black layer. How¬ 
ever, with favorable conditions upon the germinator the fungus becomes 
active and the seedling is attacked. The feeders, scutellum, and epi- 
cotyl first show symptoms of infection. 
This internal method of infection was first observed by the junior 
writer in the spring of 1920. It was observed that when the cap was 
removed increased germination free from severe infection was obtained. 
This point was thought to be the result of elimiminating the greater part 
of the internal fungus infection. It was further established that by 
disinfecting kernels after removal of cap perfect germination was secured 
in many instances. Where infection of Fusarium moniliforme and Cepha¬ 
losporium sacchari occur the internal development in the cavity under 
the cap can be recognized with a hand lens. In F . moniliforme and C. 
sacchari the abundant internal development of spores is easily determined 
by the method of crushing the lower germinal end of the kernel and making 
