In like manner we may admit theoretical views into the descriptive phraseology of other parts of Natural History: and the theoretical terms will replace the obvious images, in proportion as the theory is generally accepted and familiarly applied. For example, in speaking of the Honeysuckle, we may say that the upper leaves are _perfoliate_, meaning that a single round leaf is perforated by the stalk, or threaded upon it. Here is an image which sufficiently conveys the notion of the form. But it is now generally recognized that this apparent single leaf is, in fact, two opposite leaves joined together at their bases. If this were doubted, it may be proved by comparing the upper leaves with the lower, which are really separate and opposite. Hence the term _connate_ is applied to these conjoined opposite leaves, implying that they grow together; or they are called _connato-perfoliate_. Again; formerly the corolla was called _monopetalous_ or _polypetalous_, as it consisted of one part or of several: but it is now agreed among botanists that those corollas which {301} appear to consist of a single part, are, in fact, composed of several soldered together; hence the term _gamopetalous_ is now employed (by De Candolle and his followers) instead of monopetalous[36\4]. [Note 36\4: On this subject, see Illiger, _Versuch einer Systematischen Vollständigen Terminologie für das Thierreich und Pflanzenreich_ (1810). De Candolle, _Théorie Élémentaire de la Botanique_.] In this way the language of Natural History not only expresses, but inevitably implies, general laws of nature; and words are thus fitted to aid the progress of knowledge in this, as in other provinces of science. APHORISM XII. _If terms are systematically good, they are not to be rejected because they are etymologically inaccurate._