The Structureless Vesicles alluded to offer many further points of interest:

(a.) There is, frequently, a marked difference in the contents both of the simple vesicles, and of the individual layers of the vesicles successively ingenerated. Thus, some appear clear and colorless, others of a reddish tint; in others again, the contents are denser, pearly, or opaque, lightly granular. Some contain granules in various amount, which show themselves to be fat, - fatty conversion of the nuclei.

(b.) Of two intussuscepted vesicles the inner one is sometimes irregularly collapsed, wrinkled, or even pretty regularly indented. This probably results from a consecutive difference of density in the contents of the two, a condensation of the contents of the outer vesicle determining exosmotic effusion of the thinner contents of the inner vesicle.

(c.) Intussuscepted vesicles are, for the most part, sterile. Within their layers, however, are frequently impacted oblong, curved nuclei.

(d.) The layers are commonly smooth; often, however, gibbous, wavy, and curled.

The development of these cysts out of the nucleus, through growth of the latter, is here demonstrable even in the naked nucleus; by growth of the celled nucleus, however, it is placed beyond all doubt. Here again, the elementary granule is cognizable, as the ultimate, fundamental form; the nucleus being obviously and simply developed by growth out of the so-called nucleolus, or elementary granule.

Difficulties might, however, still arise so long as that theory of cell-formation obtains which assigns to the cell a genesis and an import distinct from those of the nucleus. If there be parent cells, their resemblance with the expanding nuclei, both in form, and often in their relation to chemical agency, might render it no easy task to determine the precise nature of a vesicle, seeing that parent cells and parent nuclei are met with concurrently. In a laminated structure, it would be peculiarly puzzling to have to decide, whether its external contour belonged to a cell, or to a nucleus-wall.

From what has been stated, however, the existence of a cancer-cyst certainly may be inferred, a cyst, namely, developed out of the elements constituting cancerous substance, and productive of cancer elements within itself. Not every cyst, however, concurrent with cancer, is necessarily of a cancerous nature, the malignant growth very possibly wearing but the character of an accidental complication.

In cysto-sarcoma the same relations obtain as to the [primitive] development of the cyst.

B. As regards the excrescences occurring upon the inner surface of the cyst, repeated observations have established the following facts: