The Structureless Cyst is developed in a consolidated, structureless blastema, commonly studded with spherical and oblong nuclei, or else in a nidus of caudate and other cells. In the former case, the cyst is speedily surrounded with a fibrous formation following the course of the encircling oblong nuclei, the cells contiguous to the cyst assuming an elongated, ribbon-like, caudate shape, and arraying themselves in parallel order around it. A remarkable tendency to enter upon this relation to the cyst is shown by the caudate cells, which constitute so many cancerous tumors. They first associate themselves one by one to very small, young, vesicles, and shortly overlay them in quite disproportionate numbers. Even oblong nuclei will fasten upon young vesicles of the kind.

5. This arrangement of the elements of a texture, brought about by the presence of young cysts, and consisting in an essential portion of those elements uniting to form capsules, and alveoli for the reception of the cysts, I have termed alveolar textural arrangement, or the alveolar textural type, and assigned to it a range extending far beyond the limits of a special heterologous formation. This establishes the distinction between the alveolar textural arrangement and many similar, but differently engendered, meshworks, cavernous structures, and the like.

6. The cyst, in its primitive state as a structureless, vesicle, and also in its development, fully corresponds with the simple gland vesicle - for example, the thyroid gland, and its development, as seen more especially in hypertrophy of the thyroid gland. Nay, the same anomalies of development, consisting in arrest and involution, are common to both. On the other side, the insensible progress of the gland-vesicle, when imbedded in its fibrous alveolus, from its normal standard to the morbid condition of a cyst, constitutes a process completely one with the secondary stage of cyst development.

7. Cysts form singly, or else collectively, in greater, often in redundant number. New cysts often arise within the fibrous wall of a parent cyst. There occurs also an endogenous multiplication of the cysts, new ones being developed in the fluid or parenchymatous contents of a cyst. In the former case, they do not in their development overstep the primitive condition, for lack of the adventitious element requisite to consolidate and advance the structureless vesicle into the true cyst.

8. The cyst, as appears under the circumstances discussed in 6, possesses, under the same form, a different import. This it reveals more especially in the character of the textural elements frequently engendered upon its internal wall through the medium of the excrescences. These repeat, now a normal, now a heterologous parenchyma - for example, that of carcinoma. We are here reminded of Hodgskin's idea, which has, from time to time, been much too inconsiderately and hastily condemned.

9. Cysts are for the most part abiding growths, which often attain to a monstrous circumference. There are, however, cysts which never, or very rarely, exceed a certain volume, about that of a grain of millet, or of a pea, at which point they burst, void their glassy, mucoid, colloid contents, perish, and are substituted by fresh ones. Exploding cysts, to which belong the cysts constituting the so-called vesicular polypi, the ovula Nabothi. The cyst in its primitive state as a structureless vesicle appears to burst, in like manner, and eject the brood elements it contained. At all events, open vesicles now and then occur which do not appear to have become so by external means.

10. On the inner surface of the cysts are found simple, bulbous or dendritic excrescences, which represent a bulb-shaped, pouch-like, or a variously projecting, hollow-growth, branching out into secondary and tertiary pouches, and consisting in a hyaline, structureless membrane, studded with spherical and oval nuclei.

These bodies shoot from the inner surface of the larger cysts, isolated or collected in groups, sometimes from the innermost, sometimes, naked, from a deeper layer, and through slight fissures, or more spacious gaps, formed by the cyst-wall giving way. Or, coming from the deeper layer, they raise the internal structureless or striated lamina of the cyst-wall into a vesicle, which they afterwards perforate, and with which they coalesce, becoming blended together with them into a meshwork. In the smaller cysts they raise up the epithelium, and retain it as an investment.

They contain an albuminous fluid, or one possessing the germs both of physiological texture, and of heterologous parenchyma. Through its accumulation they become changed into protuberant or pouch-like sacs, which last are often patent at their free extremities. There is often developed within them a fibrous texture which imparts to them the character of considerable, fleshy, shallow-lobed (condyloma-like) tumors, as in the cyst of cysto-sarcoma; or they shrivel into fibroid growths and perish. Above all they frequently engender, in the terminal bulbs of their branches, young cysts, thus mediating the endogenous production of secondary cysts.

They frequently enter upon the final transformation into a stroma of fibrous texture, which receives into a mesh work or into alveoli the elements of parenchymata of various kinds.

They occur not only in cysts, but also upon serous and synovial membranes, upon mucous membranes, growing, in all cases, into the respective cavities. Their development frequently out of deep fissures in the cyst-wall, renders it likely that they spring at some depth out of heterologous parenchymata, and ultimately penetrate into larger spaces formed by the yielding of textures.

They appear everywhere as germ-nidi, and as carriers of certain tex-tural elements. In the cyst itself their tendency is to fill up space by determining the production of physiological and pathological parenchymata, but in particular the endogenous multiplication of the cyst itself. In the vascular plexus, and in the so-called Haversian glands, they occur as physiological growths. They have sometimes the characters of a benign, sometimes of a malignant new growth.

The correlation between the chorion-villi and the cyst-formation occurring within them in the shape of acephalo-cystis racemosa of Laennec, and between the subject under discussion, is hardly to be doubted. I have, however, failed, of late, to obtain fresh materials for investigating this point.

The cyst, in its primitive state, is subject to various anomalies productive of arrest of its development, - of involution of the sac. These anomalies consist essentially in changes in the contents of the young cyst; it is therefore desirable, in the first place, to point out what is most remarkable in the contents of the cyst generally.

The first and most marked phenomenon in point, is the presence of delicate, diaphanous, for the most part simple, but also nucleated vesicles, the one kind including reddish glistening, the other kind, colorless limpid contents. In growths consisting of several cysts, encased one within the other (expanded nuclei), it is common for one or the other to include reddish contents, whilst the remainder exhibit a colorless, clear, or slightly opalescent fluid. Occasionally these different contents alternate several times. These vesicles vary from the size of a nucleolus, or a nucleus, to that of a vesicle 1/25th of a millimetre in diameter, or more. The small ones occur in all physiological and pathological fluids containing plasma; - in the blood, in the humor Morgagni, in exudates, in the juice of various heterologous growths, in the grayish blastema supplying the place of atrophied nerve-medulla in the brain and spinal tube. The larger ones occur more particularly in conjunction with cyst-growths, and as forming part of the contents of cysts.