534 ' Journal of Agricultural Research voi. xxxi, no. 6 
Under the microscope, longitudinal sections of some of the ovaries 
with infected sepals showed the mycelium present in the sepal base 
and pith of the pedicel but not within the ovary. In one case of a 
green fruit with an infected sepal the mycelium was traced from 
the edge of the sepal lesion down within the tissues of the sepal 
into the torus, a distance of 10 mm. In the case of one lopsided 
green fruit, one sepal was already killed by the fungus (pi. 3, D), 
and it was located directly above the stunted side of the fruit. 
There was no discoloration of this fruit to indicate infection, but 
microscopic examination revealed an abundance of Cladosporium 
mycelium in the fruit tissue at the stem end. 
The blackened stem-end discoloration is a rather uncommon effect 
of this fungus in greenhouses, which may be due to the fact that 
ordinarily the fruits are picked before the fungus has had time to 
grow from the sepals into the fruit,* or, if the fungus has already 
penetrated into the fruit, the fruit is disposed of before the conspicuous 
symptoms develop. The particular crop in which the fruit symp¬ 
toms were so conspicuous had been very much retarded by cloudy 
weather. 
SEED INFECTION 
The advance of the mycelium of Cladosporium fulvum from the 
stem end down through the pericarp of the fruit is paralleled by its 
penetration into the axile placentae (pi. 2, D). In some cases the 
ovules are infected and killed when very young. In cases of extreme 
atrophy of a locule in the lopsided fruits the ovules may never 
develop into seeds, even though not actually invaded by the fungus. 
Ordinarily, however, extensive invasion of the fruit occurs at a later 
stage after the seeds have developed, and the placental tissues are 
blackened and mummified by the abundant intercellular mycelium, 
while the seeds in the invaded region become darkened and many 
show a distinct blackening of the mlum end (pi. 5, A). 
Free-hand sections of the placental tissue showed the typical 
mycelial aggregates between the parenchyma cells around the 
fibrovascular bundle extending out into the funiculus of the seed. 
Longitudinal sections of a seed with a blackened hilum showed 
that the mycelium had penetrated well within the outer integument 
EXPLANATORY LEGEND FOR PLATE 5 
A. —At left: Four tomato seeds removed from the invaded stem-end region of a fruit. These are darkened 
and show blackening of the hilum. At right: Four noninfected seeds from same fruit. Enlarged X IH 
B. —A tomato seed infected at the hilum. The seed was incubated on moist filter paper in a damp cham¬ 
ber. The blackened hilum is covered with sporophores and spores of Cladosporium fulvum. Potted plants 
were infected successfully with spores from such a source. X 12 
C. —Seed coat, with blackened, infected hilum, carried up on cotyledons of seedling. The fungus was 
producing spores on the blackened tissue in this case. Enlarged X 8. In lower right corner: Primary 
infection of cotyledon from seedling grown from an infected seed such as shown in B. The cotyledon is 
covered with sporophores and spores of Cladosporium fulvum. Enlarged X 3 
D. —Longitudinal section of the hilum end of an infected seed, showing dense aggregates of brown my¬ 
celium in parenchyma tissue of middle layer of the perisperm or seed coat. The spiral vessels of the fibro- 
vascular bundle are shown. Part of the endosperm is seen at bottom. Photomicrograph X 96 
E. —Longitudinal section of hilum end of an infected seed, showing mycelial aggregates or peritheciumlike 
bodies in the funicular tissue remaining attached to the seed and also crowded between the outer integument 
and endosperm. With collapse of the parenchyma of the middle layer of seed coat, these bodies cause the 
outer integument to bulge outward. No invasion of the endosperm has been noted. (Stained with car- 
bol fuchsin). Photomicrograph X 36 
F. —Mycelial aggregates crowded between outer integument and endosperm. (From a longitudinal 
section of same seed shown in E, stained in carbol fuchsin.) Photomicrograph X 72 
G. —Longitudinal section of hilum end of infected seed, showing the intercellular mycelium in paren¬ 
chyma of middle layer of the seed coat extending down almost to the endosperm, the edge of which is seen 
at the bottom. One peritheciumlike or sclerotial body is shown at the left. (Triple stain.) Photomi¬ 
crograph X 88 
H. —Mycelial aggregates attached to exterior of seed at hilum end by entanglement of the mycelium 
with the cellulose rods or hairs of the seed coat. Photomicrograph X 81 
