Quite similar to the cases of fetus in fetu are the instances of dermoid cysts. For many years they have been a mystery to physiologists, and their origin now is little more than hypothetic. At one time the fact of finding such a formation in the ovary of an unmarried woman was presumptive evidence that she was unchaste; but this idea was dissipated as soon as examples were reported in children, and to-day we have a well-defined difference between congenital and extrauterine pregnancy. Dermoid cysts of the ovary may consist only of a wall of connective tissue lined with epidermis and containing distinctly epidermic scales which, however, may be rolled up in firm masses of a more or less soapy consistency; this variety is called by Orth epidermoid cyst; or, according to Warren, a form of cyst made up of skin containing small and ill-defined papillae, but rich in hair follicles and sebaceous glands. Even the erector pili muscle and the sudoriparous gland are often found. The hair is partly free and rolled up into thick balls or is still attached to the walls. A large mass of sebaceous material is also found in these cysts. Thomson reports a case of dermoid cyst of the bladder containing hair, which cyst he removed. It was a pedunculated growth, and it was undoubtedly vesical and not expelled from some ovarian source through the urinary passage, as sometimes occurs. The simpler forms of the ordinary dermoid cysts contain bone and teeth. The complicated teratoma of this class may contain, in addition to the previously mentioned structures, cartilage and glands, mucous and serous membrane, muscle, nerves, and cerebral substance, portions of eyes, fingers with nails, mammae, etc. Figure 64 represents a cyst containing long red hair that was removed from a blonde woman aged forty-four years who had given birth to six children. Cullingworth reports the history of a woman in whom both ovaries were apparently involved by dermoids, who had given birth to 12 children and had three miscarriages--the last, three months before the removal of the growths. The accompanying illustration, taken from Baldy, pictures a dermoid cyst of the complicated variety laid open and exposing the contents in situ. Mears of Philadelphia reports a case of ovarian cyst removed from a girl of six and a half by Bradford of Kentucky in 1875. From this age on to adult life many similar cases are recorded. Nearly every medical museum has preserved specimens of dermoid cysts, and almost all physicians are well acquainted with their occurrence. The curious formations and contents and the bizarre shapes are of great variety. Graves mentions a dermoid cyst containing the left side of a human face, an eye, a molar tooth, and various bones. Dermoid cysts are found also in regions of the body quite remote from the ovary. The so-called "orbital wens" are true inclusion of the skin of a congenital origin, as are the nasal dermoids and some of the cysts of the neck.