In The Cortical Substance Of The Kidneys, especially during the decline of Bright's disease, a luxuriating cyst-formation is not uncommon.

In the dimpled depressions upon the surface of atrophied, gibbous kidneys, reside entire nests of parallel-clustered, just discernible, poppy-or millet-seed-sized vesicles, imbedded in a reddish-gray, or whitish nidus. Occasionally the kidney is found altogether degraded into an aggregate of various-sized cysts.

A small portion of such a nidus placed under the microscope, displays along with the debris of renal texture, - namely, uriniferous tubules and Malpighian tufts, in a state of collapse or involution; the former denuded of their epithelium, and here and there replete with fat molecules - a multitude of cysts invisible to the naked eye. The more marked have parietes, consisting of fibres beset with elongated oval nuclei, which, more particularly about the inner fibre layers, bend round towards the circumference of the cyst. These cysts are replete with granulated nuclei, - now and then with spherical or polyedrical cells, to which, in some few, is superadded a molecular mass, partially betraying by its brown coloration its character as pigment granules.

In some cases this occupies the centre of the cyst, where the nuclei become indistinct and disappear. In some cysts, the nuclei (or cells) are reduced to an epithelial formation investing the cyst. In others, again, even this is wanting, and the sterile cyst is entirely filled with a clear, or semi-opaque, viscid humor. They are of very various size, from a diameter of 1/2 to 1/20 of a millimetre, the former immediately preceding vesicles distinctly cognizable with the naked eye. Conjointly with these, are found cysts, which, with similar contents and parietes, consisting of a structureless transparent membrane, reside in an equally structureless stroma, interspersed with oval nuclei, and in progress of development into a fibrillation about to encircle the cyst.

We further discern, commonly within an aggregate of spherical, nucleus-like bodies, growths of various magnitude, down to that which only just surpasses the dimensions of the nucleus. These growths quite coincide with the aforesaid structureless vesicles. The smallest contain a clear moisture, or are faintly granular. In the larger ones, a central nucleus soon appears, joined by a second, a third, a fourth, and more, so as to fill the equably dilated vesicle. This description comprises the history of the development of the cyst, and may, under favorable circumstances, be found exemplified in a single preparation. It is obviously the nucleus that grows up into the cyst; which, with reference to endogenous production, either generates brood nuclei or else proves sterile.

Besides the nuclei, there are seen smaller corpuscles of all sizes, from that of the nucleus down to that of the so-called elementary granule, and manifesting, in proportion to their magnitude, more and more of the character of the nucleus. It is, therefore, at once to be stated, that the nucleus has arisen out of the elementary granule; and this, through spontaneous germination, - not through the agglomeration of several.

Finally, we observe, in the preparation, concentrically stratified bodies, also, of different sizes, and consisting of incapsuled vesicles in varying number. These vesicles are themselves sterile, or the central vesicle may have its space occupied by one or more granulated nuclei. Sometimes it is itself represented by a nucleus. One or more of the external layers contain, in like manner, nuclei, oval in shape, and bent to a , parallel with the layer. Again, the layers are in some cases slightly gibbous. Incrustations of these forms are also present, - nay, kidneys sometimes occur, in which the cortical substance, otherwise seemingly sound, is interspersed with them, looking like yellowish, transparent grains of sand.

These are the results to which I have referred, in describing the compound cystoid. A similar result is furnished by the inspection of a group of cysts in the above-mentioned sexual attachments of the peritoneum.