MODE OF DEVELOPMENT.--It has already been stated that the fibrous tumor of the uterus grows in or on its wall and originates in the fibrous structure of the organ. The point of beginning is in one or more fasciculi of the muscular system or the connective tissue of the uterus. If in one fasciculus, the point of origin is very minute, as indeed it is generally at first. The development consists in an hypertrophy of the bundle of fibres {247} affected and a deposit of material similar in structure to that first involved. Sometimes there are numerous nuclei, and nearly all the fibrous structure of the uterus is involved in fibrous degeneration. In the case where the deposit is defined and occupies a small space, it should be borne in mind that the future tumor, however large it becomes, must occupy the same nidus in which it first originated. The nidus becomes enlarged sufficiently to accommodate the growing tumor. The nucleus of development is enlarged by the accretion of substance similar, if not identical, in character to its own proper material. The nature of the tumor is determined by this fact, and its fibres are rudimentary in organization, instead of being hypertrophied and highly developed, as those of the uterine wall by which it is surrounded. As the tumor grows the fibrous structure surrounding it is pressed aside in every direction in such a way as to completely embrace the growth and encapsulate it. The tumor does not incorporate the adjacent fibres and grow by inducing degeneration in them, but, as before said, it presses them aside. As it thus moulds and shapes a bed in the solid substance of the interior wall, it impresses upon the embracing muscular fibres an increased vitality, and they grow by hypertrophy of a character similar to that of pregnancy. The fibres become longer, and apparently, if not really, more numerous. This hypertrophy of the uterine fibres surrounding the tumor is equal to the capacity demanded by the increasing size of the growing tumor. In this description of the method of development and the embracing capacity of the hypertrophied fibres surrounding it the reader will trace the formation of the capsule in which the tumor is contained. The inner surface of the capsule is smooth, and there are many feeble fibres of connective tissue seen to connect it with the surface of the tumor. There is no adhesion proper between the surface of the tumor and its capsule.