6. Plants, like animals, have their maladies. We do not now allude to maladies caused by parasites, like the sickness of the vine, due to the _oïdium Tuckeri_, the sickness of the petals, caused by other small mushrooms, that of the rose-tree, the olive-tree, of corn, &c., produced by parasitical cryptogams, which fix themselves on the plant, and change the normal course of its life; we speak of morbid affections, properly so called. The pathological condition and its consequences exist in the plant as in the animal. Stoppage, or febrile and abnormal acceleration of the sap in the vegetable, answer to stagnation of the blood, or its acceleration during fever, in the animal; various excrescences of the bark, analogous to affections of the skin; the abortion of certain organs, and the capricious development of others; the secretion of pathological liquids which flow outside. This is a brief catalogue of the maladies to which trees, shrubs, and herbaceous vegetables are subject. A plant which passes too quickly and too often from intense cold to extreme heat, soon becomes ill, and necessarily perishes, like an animal exposed to those dangerous alterations. A shrub left in a current of cold air could no more live than an animal if kept in a similar place. In a word, the plant exhibits health or sickness, according to its conditions of existence. How can we admit that the being in which such changes take place, can be merely the passive subject of them, that it experiences neither pain nor pleasure in passing from health to sickness, or from sickness to health? 7. Sicknesses, or other causes, produce anomalies of form, or irregularities of structure in plants, as in animals. Just as in the animal kingdom _monstrosities_ exist, there are monstrosities in the vegetable kingdom. The science which occupies itself with monstrosities in animals is called _teratology_. Geoffrey St. Hilaire has made some most interesting studies of the causes of the productions of monsters in the different classes of animals; but it has been perceived of late that an analogous science must be created, for the explanation of monstrosities proper to the vegetable kingdom, and Moquin Tandon has published a book upon _vegetable teratology_.