MUCUS-CORPUSCLES.
Mucus-corpuscles. The mucus corpuscles have already been described as cells, in consequence of their resemblance to the cells of epithelium. They are round globules, enclosing a nucleus, which is eccentrical. We already know this to be the elementary form of most animal and vegetable cells, and the presence and characteristic position of the nucleus, therefore, warrant us in concluding that in this instance also the globule is a cell, although an especial cell-membrane cannot be distinguished. Giuiterbock discovered that the nucleus of the mucus-corpuscle has the peculiar property of splitting into two or three smaller corpuscles when acted upon by acetic acid, and that the enclosing or cell-membrane is gradually dissolved in the same acid. Vogel, indeed, attributes this property to such mucus-corpuscles alone as have been secreted by a morbid action, and to pus-corpuscles. But I have been informed by Henle that the true mucus-corpuscles (of which, according to him, only a very small quantity exist in healthy mucus,) exhibit the same peculiarity, and that those which are not affected by the acid are true epithelial cells. As I have never observed any other cell-nuclei to be similarly acted on by acetic acid, the fact marks the distinction between mucus and pus-corpuscles and all other cells, and, according to Henle, even the youngest epithelial cells do not possess this property, so that the mucus-corpuscles differ distinctly from them. It appears to be a characteristic of all cell-nuclei that they not only are insoluble, but do not even become transparent in dilute acetic acid. These, therefore, are peculiar cells, which are formed in the fluid of mucus as their cytoblastema, in the same manner as the yelk-cells in the fluid of the yelk-ball. They become more abundant, when the cytoblastema obtains a greater degree of "plasticity" as the result of irritation of the mucous membrane; and as on the other hand the secretions in the normal condition possess but a very small amount of plastic force, and some—the urine and bile, for instance— have not any; we accordingly find in them but a very few cells, or indeed none at all, save some cast-off epithelium. I have not investigated the question whether the nucleus exist before the cell in the mucus-corpuscles, or upon what the division of these nuclei by means of acetic acid depends.
