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collect for food. It is reported from New England to Alabama and west to Minnesota, but it may have been confused with some forms of Hygrophorus Cantharellus, which it much resembles.

Hygrophorus coccineus (Schaeff.) Fries

SCARLET HYGROPHORUS

Plate 27. Figure 7.

Pileus thin, fragile, convex to plane, obtuse, 2-5 cm. broad; surface glabrous, viscid, scarlet, fading to pale-red, and finally yellowish; flesh whitish or yellowish, edible; gills adnate or with a decurrent tooth, distant, interveined, pale-yellow or reddish; spores ellipsoid, hyaline, 6-8 × 4-5 μ; stem cylindric or compressed, glabrous, hollow, scarlet above, yellow below, 3-5 X 0.3

cm.

This brilliantly colored species occurs in moist pastures and on mossy banks in Europe and eastern North America, having been reported from Greenland to North Carolina and west as far as Minnesota.

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Pileus thin, fragile, conic, usually acute, often lobed at the margin, 2-4 cm. broad; surface viscid when moist, glabrous or fibrillose, sometimes becoming rimose, some shade of red or yellow, at times tinged with green, almost always turning black on drying; flesh thin, suffused with rosy hues; gills almost free, attenuate behind, thin, rather crowded, ventricose, yellow, blackening on drying; spores ellipsoid, hyaline, 9-11 × 6-8 μ; stem equal, fibrous-striate, hollow, yellow, becoming black on drying, 3-10 X 0.3-0.7 cm.

This species is usually readily distinguished by its conic cap with acute apex, as well as by its change of color to black on drying. It is common in moist woods and grassy places from Greenland to the Bahamas, and also occurs in Europe.

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Pileus fragile, regular, convex to plane or umbilicate, 1-5 cm. broad, surface glabrous or minutely squamulose, hardly viscid, scarlet, rarely yellow, soon fading; flesh yellow, mild, tender, edible; gills adnate or very slightly decurrent, distant, yellow often tinged with red; spores ellipsoid, hyaline, 8-9 X 4-6 μ; stem slender, equal, glabrous, concolorous or slightly paler, stuffed or partly hollow, 2-7 X 0.2-0.4 cm.

This species is very variable in color, size, and mode of growth. It may be looked for in damp woods or swamps, and is readily noticed because of its brilliant coloring. Specimens always fade to yellow on drying.

Hygrophorus Laurae Morgan

LAURA'S HYGROPHORUS

Plate 27. Figure 10.

Pileus convex to expanded, unbonate, 5-10 cm. broad; surface viscid, white, tinged with red or brown, especially on the umbo; flesh white, edible; gills white, distant, adnate or decurrent, unequal; spores ellipsoid, hyaline, 8-9 X 5-6μ; stem solid, white within, more or less curved, attenuate below, yellowish-white, scabrous above, 5-10 X 0.5-1 cm.

This species was originally described from Ohio by Morgan, but has since been found as far west as Kansas and as far east as Massachusetts, growing rather commonly in woods and groves during late summer and autumn. It represents a group of species distinguished from all the rest by a viscid, universal veil, which remains as an annulus or in the form of squamules at the apex of the stem. In the division of Fries' genus Hygrophorus, his name remains with this group and an older name, Hydrophorus Batt., is used for the viscid, hollow-stemmed species not furnished with a veil.

AN IMPORTANT ENTOMOGENOUS

FUNGUS

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H. S. FAWCETT

(WITH PLATES 28 AND 29, CONTAINING 7 FIGURES)

In 1896, H. J. Webber discovered a fungus parasite of the citrus whitefly and described its sterile form under the name of "Brown mealy-wing fungus (2)." It is now popularly known by the orange growers of Florida as the "Brown fungus" of the whitefly. The spread of this fungus on whitefly larvae,— (1) by means of superficial hyphae that spread over the surface of the leaves attacking every whitefly larva in their way, and (2) by means of spore-like aggregations of cells that may be carried in the air or by insects,-make this fungus one of the most important parasites of the whitefly! This fungus and the red fungus (Aschersonia Aleyrodis) are being introduced by orange growers into many localities in Florida with the belief that they are the most economic means yet discovered of keeping the whitefly (Aleyrodis Citri) under control.

SPREAD OF THE FUNGUS BY ARTIFICIAL MEANS

Artificial means of spreading this fungus and Aschersonia Aleyrodis have been developed by E. W. Berger, of the Florida Agricultural Experiment Station (12, 13). The two most commonly used are the leaf-pinning method and the spore-spraying method; the first consisting in pinning into a citrus tree fungusbearing leaves in contact with larva-infested leaves; the second in spraying surfaces of leaves with water contaning the spores of the fungi. The latter method has been taken up quite extensively in some orange groves. This is shown by the fact that at the present time there are men in Florida who make it a regular business to spray whitefly-infested orange trees in this way, getting their supplies of fungus spores from citrus leaves on which the fungus has previously developed upon whitefly larvae. Whenever the atmospheric conditions are favorable to

the growth of these fungi, fair success in checking the whitefly has been attained.

DEVELOPMENT OF THE FUNGUS

The fungus as it develops upon a larva of the whitefly forms a chocolate-brown (No. 10, Saccardo's Chromotaxia) stroma (pl. 28, f. 2), which to the unpracticed eye looks like the citrus red scale (Chrysomphalis Aonidum). A good description is given of this stage of the development of the fungus by Webber (2) as follows: "The hyphae develop in the body of the insect, burst out around the edges of the scale, and gradually grow up over it. In the early stage they form a brown, compact layer around the edge of the larva. As the fungus develops, the hyphae entirely cover the larval scale, forming a dense, hard, and smooth stroma. The mature stroma is compressed-hemispherical, frequently having a slight depression in the apex over the center of the insect, where the hyphae come together as they spread from the edge of the scale in their development. 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." In the later development of the fungus, the separate filamants spoken of by Webber as spreading for a distance of one half inch, grow out over the entire surface of the leaf, branching only sparingly and infecting every larva present. They extend also around the edges and over the upper surface of the leaf. These filamentous hyphae are colorless to slightly tawny with age. They are only occasionally branched, forming a loose, inconspicuous mycelium over the surface of the leaf. On the upper surface of the leaf, on short lateral hyphae, are borne the sporodochia, which are 60 to 90 μ in diameter. These consist of an aggregation of conidia-like, inflated, spherical cells, 12-18 μ in diameter. From near the place of attachment of the sporodochium, there radiate 3 to 5 hypha-like appendages, which are 150-200 μ long by 6-8μ wide, and are one- to three-septate (pl.

29, f. 5). This entire aggregation of spherical cells and appendages usually remains in union and functions as a spore. When abundant, these sporodochia present to the eye the appearance of a reddish-brown dust over the upper surface of the leaf (pl. 28, f. 1). The presence of the brown stromata may easily be known. at a distance of 10 to 20 feet by this characteristic appearance. In most cases these sporodochia are found only on the upper surface, but if the lower surface of a leaf happens to be turned over for some time they will develop there also. This condition of the fungus is common in the summer and fall. The sporodochia were first noticed in the fall of 1905, and have been observed since in great abundance every year. The supposed connection. of these sporodochia with the brown stromata was touched upon in 1908 (15), but only recently has the connection between the two been proved. The relation of the sporodochia to the spread of the fungus is interesting. When mature, the sporodochium with its accompanying appendages breaks off from the mycelium and remains upon the surface, apparently held lightly by the appendages. The inflated cells make it light, so that when once detached it blows about easily, and on coming in contact with a fairly rough surface it tends to hold fast to it. It seems probable that the appendages may also serve to hold the sporodochia to bodies of large insects that may drag them from one part of the tree to another.

GERMINATION OF SPORODOCHIA

These Aegerita sporodochia when germinated in hanging-drop cultures of sterile water and in 5 per cent. glucose solution, were seen to produce hyphae (pl. 28, f. 3, 4) identical with those which compose the brown stromata on the whitefly larvae. When germinating, the first hyphae grow out either from the sporodochia or from the ends of the appendages. These branch rather sparingly, but in a few days, in 5 per cent. glucose solution, form a network by the intercrossing of the branches (pl. 28, f. 4).

INOCULATIONS OF WHITEFLY LARVAE

Four different attempts were made to inoculate larvae of whitefly with these sporodochia, three of which were successful. One

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