2. CONIDIAL-LAYERS. (_a_) The SIMPLEST case of this is found when the conidiophores arise directly from the mycelium, parallel to one another, and form a flat body (_e.g. Exobasidium vaccinii_, _Hypochnus_; among the Phycomycetes, _Empusa muscæ_ and _Cystopus_). (_b_) In a HIGHER form the conidial-layers are thick, felted threads (_stroma_) inserted between the mycelium and the _hymenium_ (_i.e._ the region of the conidiophores). Examples are found in a section of the Pyrenomycetes (Fig. 122). (_c_) The HIGHEST form has the _basidial-layer_, that is a conidial-layer with more highly developed conidiophores (basidia). The basidial-layer, with stroma, and the hymenium (region of the basidia), forms the basidio-fructification, which is branched in the Clavariaceæ, and hat-shaped in other Hymenomycetes (in these groups the hymenium is confined to the lower side of the pileus). The hymenium of the conidial-layer and basidial-layer is composed entirely of conidiophores, or of conidiophores and sterile hyphæ (_paraphyses_) which are probably always unicellular. Paraphyses are found in _Entomophthora radicans_, and in certain Basidiomycetes (_e.g. Corticium_). 3. CONIDIOCARPS (_pycnidia_). A special covering surrounds the conidia-forming elements. The inner side of this covering (_peridium_) bears the hymenium, _i.e._ those elements from which the conidia are abstricted. The conidiocarps arise either immediately from the hyphæ or from a _stroma_ in which they are generally embedded. Conidiocarps are entirely wanting in the Phycomycetes. On the other hand they are found among the Ascomycetes and Basidiomycetes, and in the latter group the conidiocarps contain more highly differentiated conidiophores (basidia) and are known as _basidiocarps_. Conidiocarps with simple conidiophores, are found only among the Basidiomycetes, in the Uredinaceæ, and in _Craterocolla cerasi_. In the Ascomycetes (Figs. 120 _d_, _e_; 117 _a_, _b_; 123 _a_; 124 _b_) the conidiocarps are visible, as points, to the naked eye, while the basidiocarps of the Basidiomycetes (Figs. 170, 171, 173–176, 178–180) vary from the size of a pea to that of a child’s head. The “spermogonia” of the Ascomycetes and Lichenes, are conidiocarps with small conidia (_microconidia_) which germinate sometimes more slowly than other conidia, and formerly were erroneously considered as male reproductive cells, and called spermatia. The conidia of the Fungi are not primitive structures. The comparison of the sporangia and conidia among the Zygomycetes, and among the species of the genus _Peronospora_ shows, that the conidia are aberrant formations, and that they have arisen through the degeneration of the sporangium, which, by the reduction of its spores to one, has itself become a spore.