IT. TRUE TIERMAPRRODITISM.
True hermaphroditism exists as the normal type of sexual conformation in several classes of the vegetable and animal kingdom. Almost all phanerogamic plants, with the exception of those included under the class Dicecia, are fur nished with both male and female reproductive organs, placed either upon the same flower, or, as in the Linnwan class Moncecia, upon different flowers in the same individual. In the class Polygamia various exceptional genera are included, that present indiscriminately upon the same individual, or upon different indivi duals of the same species, male, female, and hermaphrodite flowers, and which thus form a kind of connecting link between the general hermaphroditic form of phanerogamie vegeta bles, and the unisexual type of the moncecious flowers, and the dicecious plants.
From anormalities in development, these normal conditions of the sexual type in the different members of the vegetable kingdom are occasionally observed to be changed. Thus, among the Diceeia, individual plants are some times, in consequence of a true malformation, observed to assume an hermaphroditic type of structure; or, on the other band, in hermaphro ditic plants more or fewer flowers are occa sionally found unisexual, in consequence of the arrested developement of one order of their sexual organs ; and again, though still more rarely, from an excess of evolution, a double set of male parts, or a double set of stamens, is seen developed on some of the individual flowers.
In the animal kingdom we find instances of a perfect hermaphroditic structure as the normal form of the sexual type in the Trematodes and Cestoides among the Entozoa, in the abranchial Annelida, in the Planaria, and in many of the Mollusca, particularly in the Pteropoda, and in several families among the Gasteropoda. In some of these animals that are thus naturally hermaphroditic, the fecundation of the female organs of the bisexual individual is accom plished by its own male organs; but in others, although the anatomical structure is strictly her maphroditic, yet the union of two, or, as some times happens, of more individuals is neces sary to complete the sexual act ; and during it the female organs of each are respectively im pregnated by the male organs of the other.
In the Nematodes and Acanthocephali among the Entozoa, and in the Cephalopoda and Pecti nibranchiate Gasteropoda among the I\Iollusea, as well as in all symmetrically formed animals, or, in other words, in those whose bodies are composed of an union of two similar halves, as in Insects, and the Arachnida, Crustacea, and Vertebrata, the male and female organs of re production are placed each upon a different individual of the species, constituting the ba sis of distinction between the two sexes. In such animals a mixture of more or fewer of the reproductive organs of the two sexes upon the same individual appears occasionally as a result of abnormal formation ; but the male and female organs that coexist in these cases are seldom or never so anatomically perfect as to enable the malformed being to exercise the proper physiological function of either or of both of the two sexes. This form of true her maphroditism or abnormal mixture upon the same individual of the organs of the two sexes in the higher animals, has been termed unnatu ral or monstrous, in opposition to the natural hermaphroditism which exists as the normal type of sexual structure in some of the lower orders of animals, and in phanerogamic plants. The malformation itself is observed to differ greatly, both in nature and degree, in different cases, varying from the presence or superaddi tion of a single organ only of theopposite or non predominant sex, up to the development and co-existence of almost all the several parts of the two sexes upon the same individual. In describing the malformation, we shall classify its various and diversified forms under the three general orders pointed out in our table, including, 1st, ; 2dly, transverse ; and 3dly, double or vertical hermaphroditism.