The internal surface of the cyst--the walls and the papillæ--is covered by a single layer of cylindrical epithelial cells, which may become flattened by pressure in the large cysts. The epithelium is often ciliated. Upon the interior of the papillomatous cyst are found warts or papillary growths. These growths vary in size from that of a grain of sand to that of the fetal head. They may be scattered over the cyst-wall or collected in groups. The larger growths often form arborescent, cauliflower-like masses, which may be so numerous and luxuriant that rupture of the cyst results. In color the papillomata vary from whitish to dark red or black, according to the vascular supply. They are sometimes yellow as the result of fatty degeneration. They are usually very vascular, and bleed freely when manipulated. The papillomata may be sessile or pedunculated. The pedicle is sometimes very long and thin. Calcification of the papillomata often takes place. Papillary cysts are usually unilocular. In any case the number of secondary loculi is much smaller than in the glandular cyst. _Fluid Contents._--The fluid contents of the papillomatous cyst differ considerably from those of the glandular cyst of the ovary. In the papillomatous tumor the contents are usually clear and of a watery consistency, with a specific gravity of from 1005 to 1040. They are not often thick, mucous, or gelatinous in consistency, as in the glandular cyst. The color varies from light yellow to dark brown from admixture of blood. As in all cystic tumors, the character of the contents depends upon the accidents that have happened during the growth of the cyst. Papillomatous cysts are more often bilateral than any other cystic tumors of the ovary. They affect both ovaries in from 50 to 75 per cent. of the cases. For this reason the operator should always carefully examine the second ovary after removing an ovarian cyst, for beginning cystic degeneration may be found in it also. Papillary cysts are usually of smaller size and of slower growth than glandular cysts. The papillomata usually perforate the cyst and invade the peritoneum before large size has been attained. These tumors, therefore, are not often seen of larger size than the adult head. Though papillomatous cysts of the ovary are not as common as the glandular cystomata, yet they are by no means unusual. The statistics of operators vary a great deal. In 600 ovariotomies Schroeder found 50 papillomatous cysts--somewhat over 8 per cent. In the experience of the writer they have been very much more frequent than this. The papillomatous cyst is the most dangerous cyst affecting the ovary. The danger lies in metastasis of the papillomatous growths to the general peritoneum. Metastasis occurs from the perforation of the cyst-wall and the escape into the peritoneum of the papillomatous masses.