The “Ferment of Wine” (_Saccharomyces ellipsoideus_) produces wine in the juice of grapes. Uncultivated yeast-cells are always present on grapes; an addition of this species to the “must” is not necessary to secure fermentation. A large number of other “uncultivated” yeast-cells appear in breweries mixed with the cultivated ones, and cause different tastes to the beer (_S. pastorianus_, etc.). _S. ludwigii_, found, for instance, on the slimy discharge from Oaks, produces abundant cell-chains on cultivation. _S. apiculatus_ is very frequently met with on all kinds of sweet fruits, it has orange-like cells. _S. mycoderma_ has cylindrical cells, often united together in chains (Fig. 183): it forms a whitish-gray mass (“fleur de vin”) on wine, beer, fruit-juice, etc., standing in bottles uncorked or not entirely filled. It is thought that this Fungus causes decomposition and oxydises the fluid in which it is found, but it cannot produce alcoholic fermentation in saccharine liquids, and it does not form endospores; hence it is uncertain whether it is true _Saccharomyces_. [Illustration: FIG. 184.--_Oidium lactis_: _a_ branched hypha commonly met with; _b_ a hypha lying in milk and producing aerial hyphæ which give rise to oidia; _c_ a branch giving rise to oidia, the oldest (outermost) oidia are becoming detached from one another; _d_ a chain of divided cells; _e_ germinating oidia in different stages (slightly more magnified than the other figures).] The “Dry-yeast” used in baking white bread is “surface-yeast.” In _leaven_, a kneaded mixture of meal, barm and water, which is used for the manufacture of black bread, _Saccharomyces minor_ is present, and a species allied to this produces alcoholic fermentation in dough with the evolution of carbonic acid, which causes the dough to “rise.” 2. =Oidium-forms.= Of many Fungi only the Oidium-forms are known, which multiply in endless series without employing any higher form of reproduction. _Oidium lactis_ (Fig. 184) is an imperfectly developed form which frequently appears on sour milk and cheese. It can produce a feeble alcoholic fermentation in saccharine liquids. Thrush or aphthæ (_O. albicans_) appears as white spots in the mouths of children. Several similar _Oidium-forms_ are parasites on the skin and hair of human beings, and produce skin diseases, such as scurvy (_O. schoenleinii_) and ringworm (_O. tonsurans_). 3. =Mycorhiza.= These Fungi, which have been found on the roots of many trees and heath-plants, particularly Cupuliferæ and Ericaceæ, consist of septate hyphæ, and belong partly to the Hymenomycetes, partly to the Gasteromycetes. It has been shown that the Mycorhiza enters into a symbiotic relationship with the roots of higher plants. DIVISION II. MUSCINEÆ (MOSSES).