Tradescantia, one of which fluids was yellowish or cream-coloured, the other strong purple, which are colours effected by the oxygenous and hydrogenous principles of light, and are constituents of the olive colours of vegetal nature commonly called green, and also analogous to the diversity of venous and arterial blood in animals; the first of which has a purple hue, and the last partakes of yellow in the composition of its colour. 890. In these, and other respects, the nature of plants verges upon that of animals,-they have a like solid and vascular organization, supported by circulating liquids,-are alike sexual and generative, the seed of each is uniform in producing its kind, in all their varieties, -the offspring resembles in each its immediate parents, yet bears an infinite diversity of features, so that neither plant nor animal exists in perfect resemblance to another of its kind; and hence in each the foundation of the culture and improvement of the race. 891. As there are carnivorous animals, so there are carnivorous plants some that live on the flesh of others, some that inhabit the bodies of others and that are incapable of sustenance upon the simple mineral soil. The analogy of animals and plants is exceedingly close; and carnivorous plants, like carnivorous animals, are common inhabitants of the swamp and the jungle. 892. Nor is the line which separates vegetal from animal nature accurately distinguishable, of which the Mimosas, or sensitive plants, on the one hand, and the Polypes and several Zoophyte aquatic productions on the other, are remarkable illustrations; and these Zoophyta, or animal-plants, have this analogy, that they are either Madripora, which are tubular; Millepora, which are cellular; or Corals, which are ramified or branched. Indeed, physiological relations are so subtile, and the gradations throughout the universe, from the lowest matter to the highest mind, are so finely marked as to require sight of more than mortal acuteness to distinguish precisely and with decision. 893. Upon the whole, too little has been contributed from the particulars of nature, and the inductions have been too narrow and few in this infinite department of physical science, to establish it upon its universal basis; we leave it, therefore, to experience to supply this deficiency, content, for the present, that no barrenness of coincidence obstructs our progress to animal science, the third and highest branch of Physics immediately connected with the present science, and that in which the analogies of nature are more abundantly unfolded and better inquired into and distinguished. CHAPTER IV. OF MEDICINE, OR ZOONICS. SECTION I. 894. THE third and last of the genera of Physical Science is MEDICINE,* or ZOONICS, which comprehend all Animal nature, as Botany does the Vegetal, and Chemistry the Mineral, or Material Nature. 895. Zoonics, or animal science, may be divided technically into Zoonomia, with respect to the kinds of animals; Zootomia, with respect to their structure, or anatomy; and Zooatria, with respect to Medicine, or the healing art; which latter professionally, and in common acceptation, comprehends the three. 896. As Chemical nature supplies materials for the sustenance of vegetals, so Botanic nature yields vegetals, by which animal nature is sustained; and these comprise the three kingdoms * We call this branch of Physical Science, Medicine, in deference to custom and the profession to which its investigation principally belongs. |