A. Lateral hermaphroditism.— According to the opinion of many physiologists of the pre sent day, the two lateral symmetrical halves of the body, and even the two halves of all its single mesial organs, are originally developed in a great degree independently of one another. Granting this point in the doctrine of eccentric developement, we can easily conceive how, in the same embryo, an ovary might be formed on one Wolftian body, and a testicle on the other; or, in other words, how female organs might be developed on one side, and male organs on the other. It is the existence of such an unsymme trical type of sexual structure upon the two op posite sides of the body of the same individual, that constitutes the distinctive characteristic of lateral hermaphroditism.
Instances of this species of true hermaphro ditic malformation have been observed in many different classes of animals, as well as in the human subject.
Individual examples are sometimes observed among insects, particularly among the Lepido ptera, in which all the different parts of the two sides or lateral halves of the body are formed after opposite sexual types. We shall after wards have occasion to notice different exam ples of this form of lateral hermaphroditism as seen in the general conformation of the body, but may hem state that in two or three in stances such malformed insects have been care fully dissected, and found to present, in the ana tomical structure of their sexual organs, a mix ture of the organs of the male and female.
In a Alelitcea didymus described by Mug,* the general external characters were those of the male, but the left eye, palpus, and antenna, and the left sexual fang, were smaller than in individuals belonging to this sex ; and the left antenna was annulated with white and yellow at the apex, while the right was of one colour. On dissection, the various male sexual parts were present, and they had appended to them a free female ovary situated upon the left, and united to no other organ.
In a Gastrophaga quereifolia dissected by Schultz, and described by Itudolphi,f the left side appeared externally male, and the right female, with a distinct line ofseparation through out the whole body. On dissection, Schultz dis covered an ovarium upon the right side, and two testes upon the left. The oviduct of the ovary joined the canal of the vasa deferentia about two inches before its termination ; and the spermatheca was connected with the com mon evacuating duct. The two testicles on the left side were placed one behind the other, and connected by a thin vessel. The spermatic
duct belonging to one of the testicles imme diately received, as in the Lepidoptera, the spi ral vessel ; further beyond, and on the opposite side, a second vessel, which appeared to con sist of the rudimental spermatic duct of the other testicle, opened into it. The oviduct of the ovary joined the canal of the vasa deferen tia about two inches before its termination in the penis, and a female spermatheca was con nected with the common distended evacuating duct./ A well-marked example of lateral herma phroditism among the Crustacca has been re corded by Dr. Nicholls.* In a lobster (Asta cus marinas) he found on the right side of the body a female sexual aperture in its normal situation at the root of the third leg, and con nected with a regularly formed oviduct, full of ova. On the left side of the animal there was a male sexual aperture placed, as usual, at the root of the fifth leg, and connected internally with an equally perfect testicle and spermatic cord. The general external conformation of the animal corresponded with its internal sexual structure, the right lateral half of the body presenting all the secondary characters and pe culiarities of the female, and the left all those of the male; so that if split from head to tail, (to use Dr. Nicholls' mode of expression,) the animal would have been perfectly female on the right side, and perfectly male on the left.
The investigations of Sir E. Hornet led phy siologists some years ago to believe that among Fishes lateral hermaphroditism constituted the natural type of sexual formation in the genera Alyxine and Petroinyzon ; but the later and more accurate observations of Ratlike: have shewn that these species are strictly bisexual, and that the opposite opinion had arisen from the kidneys of the female having been mistaken for the male testicles. Various instances, how ever, are on record of fishes, known to be nor mally bisexual, presenting from abnormal deve lopement a lateral hermaphroditic structure, or a roe on one side, and a milt on the other. Such an hermaphroditic malformation has been met with in the genera Salmo,§ Gadus,Il and Cy prinits,Ilf and in the 31crlangus vulgaris," Aci pcnser haso,tt and Esar Of lateral hermaphroditism in Birds, we have one instance recorded by Ilechstein,* in a chicken that had a testicle on the right side of the body, and an imperfect reniform ovary on the left. The external appearance of the bird presented a mixture of the characters of the two sexes.