_Habitat._--The habitat of vegetable parasitic fungi is extremely variable. Fungi are found everywhere, living and flourishing on all the families of the vegetable and animal kingdoms. They attack our houses, foods, clothes, utensils of every kind, wall papers and books, the paste of which, to my astonishment, affords a sufficient supply of nourishment. Members of the parasitic tribe of bacteria, by a combined effort of countless myriads, have given rise to a sense of supernatural agency. _Bacillus prodigiosus_, described also as _Palmella mirifica_ and _Zoogalactina imetropia_, from its attacking milk and other alimentary substances, the spores of which are often of a deep red colour, have been found to cover whole tracts of country in a single night with what is called a “_gory dew_,” changing in daylight to a deep green colour. This was at one time regarded with superstitious awe as a miracle, as it has been known to attack bread and even the sacred wafer, and which in mediæval ages was described as the “bleeding-host.” This parasitic plant belongs to anærobic bacteria, and is only developed in the dark. The nitrogen required for nutrition must be derived from the air. An algal form gives rise to the red scum seen in ponds and reservoirs in the autumn. The discharge from wounds is coloured blue by _Bacterium pyocyanine_. There are many other forms, some of which have an orange colour, and the genus is recognised as “_chromogenic microbes_.” [Illustration: Fig. 274.--Fungi and Moulds. Description of Figures.--_d._ _Puccinia graminis_ on wheat; _c._ Polycystis spore of rye-smut; _f._ Alder fungus spores, _Microspheria penicellula_; _g._ _Dactylium roseum_, rose-coloured mould; _h._ _Verticillium distans_, whorled mould found on herbaceous plants; _i._ _Botrytis_, vine and lily fungus; _j, j′._ _Peronospora infestans_, potato fungus; _k._ _P. gangliformis_, mould of herbaceous plants; _l._ Various _Penicillium_ and other spores taken in a bean-field.] A cryptogam belonging to anærobic bacteria, described as _Protococcus invalis_, on being set aside in a bottle, and a little rain water added, was seen to set up spontaneous fermentation, and in a very short time exhibited remarkable activity. The colour of the infusion changed, it assumed a delicate pink hue in direct light, which deepened to a red in reflected light. The fluid contents were now observed to be dichoric, and the spectroscopic appearance subsequently presented was one of much interest. The spectrum was a well-marked one, and might be taken to determine the presence of a nitrogenous element or of glucose.