Order 3. =Thelebolaceæ.= _Thelebolus stercoreus_, is found on the dung of deer, hares, and rabbits, and has _closed sporangia_, which resemble asci in their shape and regular construction, and in the ejection of spores. The covering encloses only one sporangium, even where the sporangia arise close together. This order, by reason of the covering of the sporangia, forms the transition from the Hemiasci to the Carpoasci, while the two first supply an intermediate step to the Exoasci. Sub-Class 2. =Hemibasidii, Brand-Fungi.= The Brand-Fungi (also known as USTILAGINEÆ) are Fungi with _basidia-like conidiophores_, which, however, have not yet advanced to a definite form or number of conidia. They are true parasites, whose mycelium spreads itself in the intercellular spaces of Flowering plants. The mycelium is colourless, quickly perishable, has transverse walls at some distance from each other (Fig. 96), and sends out haustoria into the cells of the host-plant. [Illustration: FIG. 96.--_Entyloma ranunculi._ 1. Cross section of a portion of a leaf of _Ficaria_ permeated by the mycelium; a bundle of hyphæ with conidia emerging from a stoma; in one of the cells are found four brand-spores. 2. A brand-spore developed in the middle of a hypha.] It most frequently happens that the germ-tube enters the host-plant at its most tender age, that is, during the germination of the seed; the mycelium then wanders about in the tissues of the shoot during its growth, until it reaches that part of the plant where the spores are to be formed. The spore-formation takes place in the same way in all those species whose brand-spores are developed in the floral parts of the host-plant. Many Brand-Fungi have, however, a more local occurrence, and the mycelium is restricted to a smaller area of the leaf or stem. Those organs of the host-plant in which the brand-spores are developed often become strongly hypertrophied. In perennial plants the mycelium winters very often in the rhizome. [Illustration: FIG. 97.--_Doassansia alismatis._ 1. A fruit-body, formed by a covering of oblong hyphæ, which encloses a mass of brand-spores, and is embedded in the leaf-tissue of the host-plant; 20 times natural size. 2. A germinating brand-spore, 500 times natural size. 3. Three connected resting-spores, 400 times natural size. 4. Two conidia grown together, 600 times natural size.]