Now to the first question—whether these delineations were wanted? I support the affirmative by appealing to all those of the profession who have had occasion to be consulted in cases of abortion and the expulsion of those singular productions of the uterine cavity, which seem connected with menstruation or faulty conception. Let them say whether a work, in which the principal of the infinitely varied aborted human ova, and of the uterine productions alluded to, are faithfully represented, be not likely to be useful; whether, in fact, it be not wanted—or whether it exist already anywhere. If the want of such a work be made manifest, its importance must be self-evident. But that importance is not a little enhanced when we find Denman—a plain unsophisticated practitioner—with quite enough of science to constitute him an authority in physiological questions concerning human generation,—recommending the inquiry, in his own work on an analogous subject, entitled “Engravings representing the Generation of some Animals”, in which he has given three drawings of aborted ova. “It must be allowed”, observes the Doctor, “that the generality of these things (the aborted ova) are preserved for their beauty, or as matter of curiosity, rather than of use. I suspect, nevertheless, that there are some appearances besides the _vesicula umbilicalis_ not yet perfectly understood, and therefore recommend the whole subject as worthy of being reviewed”: and, in a subsequent part, he says, that “in every collection there must be some example, which may enable us to distinguish the different parts of which an ovum is composed, the proportion which they bear to each other at different periods of pregnancy, and sometimes the process of utero gestation which failed”. What greater encouragement, therefore, needed I than this opinion and advice of one of the best obstetricians England can boast of, to select, prepare, and point out the importance of this species of anatomical and physiological delineations? I shall conclude, by remarking, that the plates are intended to illustrate a work “On Abortion and the Diseases incidental to Menstruation”, which I have been preparing for several years, and a prospectus of the contents of which will be found at the end of the present volume. That work will appear, DEO favente, in the course of the present year; but for the convenience of such persons as may not feel inclined to purchase it, the collection of plates has been purposely so arranged, as to be published, with a corresponding text, in a separate form, and independently of the forthcoming volume. _Grafton-street, Berkeley-square, 30th March, 1833._ PROLEGOMENA OF THE DEVELOPMENT AND METAMORPHOSES OF THE HUMAN OVUM. PROLEGOMENA.