Mycological System

On the other hand, a position in the System indicates nature and character more than a description does. This seems to be easily expressible by formulas, as you will find below in the Conspectus of the Mycological System. The relations of the 4 cosmic moments (these are the reproductive effort, air, heat, light), from which the fungus is determined, are expressed by four letters; these are intimately connected with the 4 essential characters of fungi. — The formula of Polyporus is $HH^2U$; it not only indicates the character ($H$ being that the hymenium is the most essential, i.e., the Class; $H^2$ the receptacle, dilated above by means of light, sterile, i.e., the Order; $U$ that the hymenium is porous (uterine), conjoined with the pileus (the genus)); but it also indicates the entire evolution, the native location on dried wood, etc. A single changed letter indicates all the differences of Agaricus. We do not understand a genus whose formula is hidden; once this is given, we perceive its entire harmony.

Any section that best expresses the character of the one above it (i.e., that which presents the organ of the section's type most perfectly evolved, so that it excels or often excludes the others taken together) is called the Center. From this, it also follows that it is the most distinct from the remaining sections. Relations with other essential organs also change less here, and hence the species in the center turn out to be more similar. Therefore, central genera, the order of the type, are always the most vast (Agaricus, Fucus, Lichen in the sense of Wahlenberg, Hypnum, etc.) and are much more difficult to divide into several genera than the radii, which are sections (genera, orders, etc.).