Recherches sur le développement et l’histogenèse dans les Astérosporales

In Lactarius, as well as in at least some species of Russula, the development of clumps of spherocysts, occurring in the trama of the carpophores is initiated by the formation of structures which, as seen in section, resemble rosettes. These consist of a central hypha sheathed with small spherocysts. The clumps of spherocysts in Russula are in general much larger, and usually more primary rosettes are involved. This condition contrasts with the narrow complexes in Lactarius which are drawn out longitudinally and generally arranged round the axis of the primordium, at least in the stipe. The central hypha is believed to induce locally the formation of chains of spherocysts by exerting directional influence upon the surrounding protenchymatic hyphae while stimulating them to produce cells. After this action the central hypha soon disintegrates. Clumps of spherocysts occur also in the rudimentary stipe of Arcangeliella and in Elasmomyces; it is probable that here, too, a certain hypha is responsible for their formation. The complicated construction of the trama of the Asterosporales may correspond with some structures generally present in the bulbs of Agaricales consisting of knots of much entangled hyphae with short cells, curving and winding hyphae and many free ends of hyphal ramifications. In the primordia of Asterosporales a considerable portion of the trama consists of a similar intricate and polymorphous tissue, parallel hyphae being found only at the extreme margin of the pileus and in the trama of the gills. The majority of the cystidia of Russula is homologous to hairs, one of the functions of these elements being the protection of the primordium against exsiccation.