The fundamental substance or stroma is colorless and homogeneous.
The coloring matters are not dissolved in the stroma of the chrornoplast, but exist as amorphous granules, with or without the presence of a protein crystal, or in the form of fine crystalline needles, frequently curved and sometimes present in large numbers, which are grouped together in various ways in bundles and give the plastids their fusiform or triangular crystalline shape.
Deep to these is the ovarian stroma, composed of fibrous tissue, and embedded in it are numerous nests of epithelial cells, the Graafian follicles, in various stages of development.
Here we have the cushion-like type (stroma) of Nectria and many Pyrenomycetes, the clavate "receptacle" of Clavaria, &c., passing into the complex forms met with in Sparassis, Xylaria, Polyporei, and Agaricini, &c. In these cases the compound sporophore is often termed the hymenophore, and its various parts demand special names (pileus, stipes, gills, po--es, &c.) to denote peculiarities of distribution of the hymenium owlthe surface.
Other series of modifications arise in which the tissues corresponding to the stroma invest the sporogenous hyphal ends, and thus enclose the spores, asci, basidia, &c., in a cavity.
In the simplest case the stroma, after bearing its crop of conidia or oidia, develops ascogenous branches in the loosened meshes of its interior (e.g.
Another simple case is where the plane or slightly convex surface of the stroma rises at its margins and overgrows the sporogenous hyphal ends, so that the spores, asci, &c., come to lie in the depression of a cavity - e.g.
In other cases (Hypomyces, Nectria) the perithecia arise on an already mature stroma, while yet more numerous examples can be given (Poronia, Hypoxylon, Claviceps, &c.) where the perithecia originate below the surface of a stroma formed long before.
The simpler forms bear the perithecia directly on the mycelium, but the more highly developed forms often bear them on a special mycelial development - the stroma, which is often of large size and special shape and colour, and of dense consistence.
(Orlando Bandinelli), pope from 1159 to 1181, was a Siennese, and as a teacher of canon law in Bologna composed the Stroma or the Summa Magistri Rolandi, one of the earliest commentaries on the Decretum Gratiani.