526 
Journal of Agricultural Research 
Vol. XXXI, No. 6 
doparenchyma. Makemson (S, p. 321) noted this type of stroma 
formation in his cultures on corn kernels, and it seems to be of com¬ 
mon occurrence in culture. 
In the larger intercellular spaces in the fruit tissue, not only 
immediately under the epidermis but throughout the interior tissues 
as well, this production oi a pseudoparenchyma by the fungus reaches 
its maximum, and results in the formation of more or less spherical, 
stromatic, or sclerotial bodies just mentioned (pi. 3, B; pi. 4, D, E). 
Eventually these bodies become spherical and peritheciumlike, 
having an outer wall and oily contents, and measuring from 150 to 300 
microns in diameter. Makemson (£, p. 323) noted the smaller 
stromatic bodies in the leaves, and found the larger bodies in his 
cultures on corn kernels. He (£, p. 320) describes the latter as 
“spherical bodies ranging from 50 to 120 microns in diameter” pre¬ 
senting “ a structure typically perithecial in appearance with a thin, 
E seudoparenchymatous wall.” These bodies, he states, were partially 
ollowWt “contained neither asci nor spores, and could not be made 
to form spores by ordinary variations in the cultural technique.” 
In a culture on an autoclaved apple twig resting on moist cotton in 
the bottom of a test tube, these sclerotial bodies had developed in 
abundance on the cotton fibers at the end of 39 days. They had 
a dense dark brown wall and oily contents, and were accompanied by 
an abundance of short-celled, thick-walled, brown mycelium. These 
sclerotial or peritheciumlike bodies resemble in many ways the 
bulbils of certain fungi described and illustrated by Hotson (5 ). The 
formation of such bodies is apparently not uncommon among other 
Cladosporium species. Humphrey {6, p. 228) described hyphal knots 
formed by Cladosporium cucumerinum E. and A. in cucumber leaves, 
and Keitt (7, p. 13) found sclerotioid bodies formed by C. carpophilum 
Thum. 
Cross sections of a tomato-leaf lesion near the midrib show that the 
fungus forms similar, but much smaller, mycelial clumps in the 
intercellular spaces of the mesophyll and in the substomatal chambers 
(pi. 4, A). Those in the latter position project or grow out through 
the stomata and bear tufts of sporophores, as Makemson (8 } p. 323) 
has -reported. A similar intercellular accumulation of mycelium 
occurs in the sepals, pedicels, and torus, in fact in all tissues in which 
the collapse and deatn of the host cells does not occur very soon after 
invasion. 
EXPLANATORY LEGEND FOR PLATE 4 
A—Cross section of a leaf lesion of Cladosporium, fulvum , showing dense intercellular aggregates of 
mycelium in the mesophyll and tufts of sporophores borne on mycelial aggregates or stromatic bodies in 
the stomata. The greater production of sporophores occurs on the lower epidermis. Photomicrograph 
X no 
B. —Stromatic bodies covered with short sporophores. These bodies have pushed through the epi¬ 
dermis of the fruit in one of the white, papery lesions such as shown in Plate 2, C. In general the bodies 
remain subepidermal in the fruit lesions. Photomicrograph X 88 
C. —Longitudinal section through cortex of an infected pedicel showing dense aggregates of mycelium 
between the cortical parenchyma cells adjacent to the vascular tissue (phloem) at the right. Photomicro¬ 
graph X 88 
D. —Enlarged view of the region marked O in the pericarp section in E, showing the multiple strands of 
mycelium between the cells and an intercellular sclerotial body 160 n in diameter. Photomicrograph 
X 108 
E—Cross section through outer portion of pericarp showing intercellular network or reticulum of com¬ 
posite mycelial strands. Tissue is so thoroughly infested that it is somewhat mummified, the cavities 
in the reticulum representing the original host cells. Scattered sclerotial bodies occur at various points, 
apparently in the larger intercellular spaces. The body at O is shown enlarged in D. Photomicro¬ 
graph X 35 , , 
F.—Cross section of an infected pedicel 3 mm. above the torus, showing dense masses of mycelium 
between the parenchyma cells of inner half of cortex, illustrating tendency of this fungus to accumulate 
near, but not within, the vascular tissues. Photomicrograph X 96 
