The Encysted Parenchyma is often contained free within the cyst space; sometimes, however, there is present a meshwork, issuing from the inner wall of the cyst, the spaces of which are filled up with the medullary mass. This framework consists of a transparent striated blastema, pervaded by numerous spherical and oblong nuclei, and breaking up into fibrils. Simple hollow bulbs shoot up from its trellises, and into its chamberlets. Respecting the development of this stroma, two theories might be propounded:

(a.) It might result from a continuous separation of the internal layer of the cyst-wall.

(b.) It is, however, far more probable that, like the framework of alveolar gelatinous cancer, or of the encysted new growth of thyroid gland parenchyma in goitre, it results from the blending of the excrescences concentrically growing from the inner surface of the cyst.

Occasionally, sharply-defined, spheroid cancer tumors occur in which no cyst-wall is discoverable, but yet, in their interior, a stroma of this kind. It is very probable that these tumors were previously encysted cancer-masses, from which the cyst has, owing to a total disruption with excessive production of those excrescences, disappeared or become part and parcel of the stroma.

The repeated examination of so-called alveolar cancer (gelatine cancer in alveolar form) offers very interesting results, corroborative of the endogenous multiplication of its cysts. Besides the exogenous augmentation, there occurs likewise an endogenous one, the medium of which is offered by the often-mentioned excrescences; and in this process these become converted into the framework, in the alveoli of which the small cysts are subsequently lodged. From the inner surface of a thick-walled follicle, or alveolus, numerous simple bulbous pouches shoot up into it, so as to penetrate it. Another, contiguous, is replete with a young delicate alveolar parenchyma. In the interior of those hollow bulbs is seen one, or a pair of cysts. In such prolific cysts the development of the fibre-layer for the young cysts may often be seen proceeding from the base of the excrescences, near the inner wall of the parent follicle. Gluge has seen these bulbous pouches in a cancer of the rectum, and figured them. Owing, however, to his treatment of the preparation, he recognized neither their relation to the alveoli nor their character in general. He regards them as altered and hypertrophied muciparous glands.

Thus, encysted alveolar cancer is accounted for and explained in the same manner as medullary carcinoma.

4. Upon The Internal Parietes Of Cysto-Sarcomata

Upon The Internal Parietes Of Cysto-Sarcomata there are known to occur (in the so-called cysto-sarcoma proliferum) warty, foliaceous, ' bulbous vegetations, as also pedunculate cysts. The former often attain to a considerable size, so as to fill up the space of the cyst, presenting a flesh-like aspect. [For an explanation of these phenomena, the reader is referred to an appendix to the separate section on cysto-sarcoma.~\

5. In Goitre

In Goitre, besides others, there occur cysts filled with thyroid gland parenchyma of accessory growth. We have often the opportunity of witnessing the process of this endogenous production in its incipient stage. From the inner parietes of the cyst arise delicate, transparent, protuberant, vascularized excrescences, in the interior of which a new creation of gland-vesicles takes place.