Of the six families of the Carpoasci, the first three--_Gymnoascales_, _Perisporiales_, and _Pyrenomycetes_--are ANGIOCARPIC (that is, the ascocarp remains closed throughout its existence, and does not dehisce when ripe); the fourth and fifth families (_Hysteriales_ and _Discomycetes_), on the other hand, are HEMIANGIOCARPIC (the ascocarp, here also called an _apothecium_, is closed in the early stages, but opens at the commencement of ripening and exposes a hymenium of crowded asci); the family of _Helvellales_ has probably GYMNOCARPIC (or hemiangiocarpic) fruit-bodies. Family 1. =Gymnoascales.= The ascocarps are surrounded by a _spongy and incomplete envelope_. One order, poor in species. Order =Gymnoascaceæ=.--The ascocarps are borne sometimes solitarily, or sometimes coiled together. _Gymnoascus reessii_ forms small bodies about 1 mm. in diameter on old horse-dung, which at first are white and afterwards orange-red.--_Ctenomyces serratus_ lives on the old feathers in birds’ nests. Family 2. =Perisporiales.= The ascocarps are surrounded by a _complete envelope_ without any opening: the fruit-bodies are cleistocarpic; the spores are only liberated after the disintegration of the fruit-bodies. Paraphyses are wanting. The two first orders have in addition the means of reproduction by conidia. Order 1. =Erysiphaceæ, Mildews.= The Fungi belonging to this order are epiphytic parasites, whose mycelium, somewhat resembling a cobweb, may be seen on the leaves and other green portions of plants (see Figs. 107, 108). The hyphæ ramify in all directions upon the surface of their host, and emit haustoria which penetrate the epidermal cells, and thus derive the necessary nutriment. The Mildew-Fungi thus belong to the obligate parasites, and during their growth dwarf and destroy the portions of their host on which they live. The reproduction takes place in the first instance by abstriction of conidio-chains from the end of special branches (Fig. 108 _c_, a hypha is seen in the act of detaching a conidium). The conidia may germinate immediately, and thus quickly reproduce their species. When present in large numbers they appear as a white meal covering the surface of the plant on which the fungus is found. Later on appear the dark brown, spheroid ascocarps (Fig. 108 _a_) which, although small, are generally just visible to the naked eye as black specks. [Illustration: FIG. 107.--_Erysiphe cichoracearum_: _a_ mycelium-threads; _b_ sterile hypha (“pollinodium”); _c_ fertile hypha (ascogone or archicarp); _d_ and _e_ young ascocarps.]