14. _Dothidea typhina_, capsules (perithecia). 15. _Dothidea typhina_, ascus containing spores. 16. _Sphæria rubella_, on nettle-stem. 17. _Sphæria rubella_, asci. 18. _Sphæria rubella_, capsules (perithecia). 19. _Sphæria rubella_, ascus and spores. 20. _Sphæria bullata_, on piece of stick; 20 _a_, section of tubercle (receptacle). 21. _Sphæria bullata_, asci and spores. 22. _Sphæria complanata_, on piece of stick. 23. _Sphæria complanata_, tubercles (receptacles). 24. _Dothidea ulmi_, on elm-leaf. 25. _Dothidea ulmi_, asci. 26. _Dothidea ulmi_, section of receptacle. 27. _Dothidea ulmi_, spores. 28. _Chætomium elatum_; 28 _a_, spores; 28 _b_, filaments. 29. _Chætomium elatum_, on piece of stick. 30. _Hysterium fraxini_, on piece of stick. 31. _Hysterium fraxini_, receptacle. 32. _Hysterium fraxini_, ascus with spores. 33. _Erysiphe guttata_, on hazel-leaf. 34. _Erysiphe guttata_, capsule. 35. _Erysiphe guttata_, capsule (conceptacle) with fulcra. 36. _Mucor mucedo_: _a_, columella; _s_, spores. 37. _Acrostalagmus_: _a_, spores. 38. Gall on oak-leaf. 39. Gall on oak-leaf. [Illustration: Plate VIII. _W Bagg sculp_ _London: John Van Voorst._] MUCED´INES.--Many of the Fungi belonging to this family are extremely common on decaying vegetable substances, and some are found upon living plants, to which they are very injurious. To the naked eye they usually appear as mouldy or cottony masses, either white, black, or coloured blue, yellow, &c. The spores are attached singly or in rows to branchlets arising from the ends of the filaments, so as to form little heads. _Bot´rytis parasit´ica_ (Pl. VII. fig. 19) is common upon the flower-stalks of the Shepherd’s Purse, forming white mealy patches. The fruit-stalks are comparatively large and thin-walled, the branchlets being slender, mostly curved, and terminated each by a large, spherical, smooth, simple, white spore. _Botrytis vulgáris_ is also common on various decaying plants. Its filaments are grey, and the branchlets lobe-like; the spores being minute, spherical, either white or greenish, and placed simply at the tips. _Botrytis infes´tans_ is the potato-Fungus. It forms white spots upon the under side of the leaves of the potato-plant, and by some authors is considered to be the cause of the potato-disease. The filaments are branched at the ends, and terminated by single oval spores, which are apiculate at the free end, and contain minute little spores or sporidia. _Oid´ium Tuck´eri_ is the well-known destructive grape-Fungus. It forms white cottony masses upon the vine and its grapes, the fruit-stalks being short and terminated by one or two end-to-end oblong spores. It appears to be the Coniomycetous form of another Fungus (_Erysiphe_).