THE BROWN FUNGUS. 29 
gist, who, under date of November 2, 1907, wrote: "The specimen 
has a fruiting stage connected with the brown fungus/' In a publi- 
cation dated October 1, 1908, Prof. Fawcett 1 announced that he 
had noted what appeared to be the spores of the brown fungus, and 
that these spores were then germinating in hanging drop cultures of 
sugar solutions, and were producing hypha3 that seemed identical 
with those of the brown fungus. Since then, however, Prof. Fawcett 
has been most successful in not only growing the characteristic 
brown-fungus mycelium from the spores, but infecting healthy white- 
fly larvae with the mycelia thus grown and in securing the charac- 
teristic pustules of this fungus, to which he has given the name 
Mgerita wehheri. 2 
DESCRIPTION. 
The pustules of the brown fungus, which vary in size according to 
the size of the larva or pupa infected, are seal-brown in color and 
when fully developed entirely conceal the insect attacked. The 
pustules are round or slightly elliptical, and, as compared with the 
pustules of the red Aschersonia, are more flattened, thus resembling 
the Florida red (or circular) scale (CJirysompJialus ficus) (see PI. I, 
lower figure; also PI. VII.) Dr. Webber gives the following general 
description: 3 
The mature stroma is compressed hemispherical, frequently having a slight depres- 
sion in the apex over the center of the insect, where the hyphae come together as they 
spread from the edges of the larva in their development. The size varies greatly 
according to the stage of development of the insect attacked. In many young larvae 
it is from one- fourth to one-half a millimeter in diameter. The thickness or height 
also varies in like manner, specimens on mature larvae or pupae having usually from 
175 to 260 microns while those on young larvae are much thinner. * * * The 
stroma is commonly seal brown, with a shade of chestnut, but becomes slightly darker 
with age. It adheres closely to the leaf, but no indication has been found that the 
hyphae penetrate the latter. The hyphae which make up the body of the stroma are 
light brown, very tortuous, and but slightly branched. 
Those in the body of the insect are of similar character, but a much darker brown. 
From the base of the stroma a ground mycelium, or hypothallus, spreads out in all 
directions on the surface of the leaf, forming a compact membrane near the stroma, 
but becoming gradually dispersed into separate filaments. * * * The hyphae of 
the hypothallus are colorless, sparingly branched, mostly continuous, having only an 
occasional septa, and are from 5 to 7 microns in diameter. In some places in the 
hypothallus, when the hyphae are apparently somewhat amassed and knotted, they 
become light brown, similar in color to the isolated hyphae of the stroma. * 
When there are but a few pustules on a leaf, the threadlike myce- 
lium spreads as separate strands on the underside of the leaf 
for as far as 2 or 3 inches and may be seen with the aid of a 
lens. The mycelium also often extends to the upper surface of the 
leaf. When the pustules are abundant, however, the mycelial 
1 Univ. of the State of Florida, Special Studies No. 1. 
2 An important entomogenous fungus. Mycologia, vol. 2, no. 4, July, 1910. 
8 Bui. 13, Div. Veg. Phys. and Path., U. S. Dept. Agr., pp. 28-30, 1897. 
