THE BROWN FUNGUS. 29 



gist, vfho, imdor date of Xovoinbor 2, 1907, wroto: "Tlio spociiiKMi 

 has a fruiting stage coiiucctod with the brown fungus." In a ])ul)li- 

 cation dated October 1, 1908, Prof. Fawcett' announc.etl tJiat lie 

 had noted what aj)i)eai"e(l to be the spores of tlie brown fungus, and 

 that tliese spores were then gerinuiating in hanging (h"o}) (cultures of 

 sugar solutions, and were producing hyi)lia) that seemed identical 

 with those of the brown fungus. Since tluMi, liowever, Prof. Fawcett 

 lias been most successful in not only growing the characteristic 

 brown-fungus m3''celium from the spores, but infecting liealthy white- 

 lly larviTB with the mycelia thus grown and in secuiring the charac- 

 teristic pustules of this fungus, to which he has given the name 

 Mgerita wehheri.^ 



DESCRIPTION. 



The })ustules of the brown fungus, which vary in size according to 

 the size of the larva or ])upa 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 llattened, thus resembling 

 the Florida red (or circular) scale (Chrysom phalus Jicus) (see PI, I, 

 lower figure; also PI. VII.) Dr. Webber gives the following general 

 description: ^ 



The mature stroma is compressed hemispherical, frequently having a slight deprea- 

 eion in the apex over the center of the insect, where the hyphoe come together aa 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 larvse or pupae having usually from 

 175 to 260 microns while those on young larvse 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 

 hyphse penetrate the latter. The hyphse 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 hj'phse are apparently somewhat amassed and knotted, they 

 become light brown, similar in color to the isolated hyphae of the stroma. 



"\Ylien there are but a few pustules on a leaf, the threadlike myce- 

 hum 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 cntoniogcnous fungus. Mycologia, vol. 2, no. 4, July, 1910. 

 « Bui. 13, Uiv. Veg. Phys. and I'atli., U. S. Dept. Agr., pp. 28-30, 1897. 



