As to internal structure, there is a dissolution and disappearance of the paraphyses in some genera, their protective function not being so necessary in closed fruits, a character paralleled in fungi. There is a great variety of spore changes, from being minute, simple and colourless, to varied septation, general increase in size, and brown colouration. The different types may be traced to fungal ancestors with somewhat similar spores, but more generally they have developed within the lichen series. From the life of the individual it is possible to follow the course of evolution, and the spores of all species begin as simple, colourless bodies; in some genera they remain so, in others they undergo more or less change before reaching the final stage of colour or septation that marks the mature condition. As regards direct fungal ancestors, the Pyrenocarpineae, with solitary perithecia, are nearest in fruit structure to the Mycosphaerellaceae, in which family are included several fungus genera that are parasitic on lichens such as _Ticothecium_, _Müllerella_, etc. In that family occurs also the genus _Stigmatea_, in which the perithecia in form and structure are very similar to dimidiate _Verrucariae_. Zahlbruckner[982] has suggested as the starting point for the Verrucariaceae the fungus genus _Verrucula_. It was established by Steiner[983] to include two species, _V. cahirensis_ and _V. aegyptica_, their perithecia being exactly similar to those of _Verrucaria_[984] in which genus they were originally placed. Both are parasitic on species of _Caloplaca_ (_Placodium_). The former, on _C. gilvella_, transforms the host thallus to the appearance of a minutely lobed _Placodium_; the latter occupies an island-like area in the centre of the thallus of _Caloplaca interveniens_, and gives it, with its accompanying parasite, the character of an _Endopyrenium_ (_Dermatocarpon_), while the rest of the thallus is normal and fertile. Zahlbruckner may have argued rightly, but it is also possible to regard these rare desert species as reversions from an originally symbiotic to a purely parasitic condition. Reinke came to the conclusion that if a parasitic species were derived directly from a lichen type, then it must still rank as a lichen, a view that has a direct bearing on the question. The parallel family of Pyrenulaceae which have _Trentepohlia_ gonidia is considered by Zahlbruckner to have originated from the fungus genus _Didymella_.