PUT FORTH BY VALENTIN. 223
Pigment-globules of a black colour are soon, however, developed on their periphery, so that the corpuscles or vesicles just mentioned are transparent in their centre when they have ceased to be so, and have become dark on their circumference. It is plain that von Ammon and R. Wagner have seen this condition as well as myself. The globules are so small from the commencement, that they ..... This process of deposition of the black-coloured globules upon the pigment-corpuscles goes on afterwards continuously, and to such an extent that the latter are enveloped and covered on all sides by them, and are only
rendered visible when the globules are removed by pressure or washing.);——and I compared the pigment-cells with the cellular tissue of plants. (Repertor. ii, 245. The pigment here (in the choroid) has the same character which it has in most other parts of the body, that is, a round, clear, transparent, and colourless nucleus, or the pigment-molecules lie closely crowded together around a pigment-vesicle. These
heaps of pigment composed of pigment-vesicles, and the molecules of pigment deposited around them, are extended out sidewise, and in man, the dog, the rabbit, the horse, the ox, and such like, form unequal pentagons or hexagons, which are placed close together in a similar manner to the cells of the parenchymatous cellular tissue of plants. Langenbeck de retina, 38.) Schwann gave an essential completeness to these analogies, by showing that the gelatinous primordial mass of the tissues was composed of cells, that the bodies imbedded init are nuclei, and that these and the cells often exhibit analogous laws of development. (Froriep’s Notizen, 1838, Mikroskopische Untersuchungen über die Struktur der Thiere und Pflanzen, Heft i, 1838.) As early as 1837 I had observed the cells of the germinal membrane in the ovum of sepia, with their nuclei and nucleoli, and the areas surrounding them, and had communicated my researches in a letter to Breschet. Shortly after I became acquainted with Schwann’s first communication I commenced the investigation of the subject. The chief results of my inquiries are contained in the following communication. I have, at the same time, referred to the corresponding passages in the first part of Schwann’s treatise, which I have received this day.”
I will only add that the second part also, (consisting of sheets 8 to 13, and Plates III and IV,) therefore the whole of the portion of my treatise containing the observations, had appeared previous to Valentin’s researches, and had been communicated to the Parisian Academy in the year 1838; a remark which does not appear altogether superfluous, since Professor Wagner has
