222 REMARKS UPON A STATEMENT
more difficult to detect the cell-shaped and more rounded globules, although they are quite as certainly present. When the object has not been at all damaged, the cells, and especially the pigment-globules adhering to the outside, exhibit an arrangement like that of the vegetable cells in general, and particularly in the earliest stages in the formation of the leaf, that is, a disposition corresponding to spiral lines projected on the surface in accordance with the strictest rules) —— compared to the cellular tissue of plants, I chose, expressly (l.c. 77. Each of these globules (ganglion-globules), wherever observed, has an external, more or less distinct, areolar tissue-like envelope, and contains a parenchymatous mass proper to itself, an independent nucleus or kernel (nucleus oder Kern), which again encloses a second roundish, transparent nucleus)——on account of this resemblance in form, the uniform appellation of the nucleus (Kernes), just as I afterwards described the nucleolus which was observed by me. (Repertor. i, 143. In every cell without exception there is a somewhat smaller and more compact nucleus of a round or oval form. It usually occupies the centre of each cell, consists of a minutely granulous substance, but encloses a well-defined, round corpuscle, which thus forms a sort of second nucleus within it.)In the study of the epithelia, prosecuted particularly by Henle and myself, there was no want of analogies with vegetable cellular tissue, the individuality of the cell-parietes was also distinctly demonstrated. (Ib. 284. Roundish, hexagonal, flat, and tolerably thin cells lie (in the external skin of the proteus) close upon one another, disposed in regular arrangement, and always connected together with their lateral edges and angles in mutual correspondence. The interior of these delicate bodies is filled by a granulous or yellowish mass, which represents a sort of nucleus. But the separate granules of this nucleus, however closely they may he together, may be accurately distinguished from one another. With a very strong magnifying power, each one of these granules may be seen to be more transparent in its centre than it is in its periphery. It may then also be most distinctly ascertained, that the somewhat delicate parietes of each cell are perfectly isolated from the central cavity. No trace of granules or fibres can be observed on the walls themselves; there is merely a clear, transparent, vitreous, and homogeneous mass.) I had also remarked that the nuclei (pigment-vesicles) were the parts first formed in the pigment of the choroid coat (Entwickelungsgeschichte, 194. The following is the mode in which, according to my observations, the stratum of pigment is formed in man, mammalia, and birds; separate, round, colourless, and transparent corpuscles are first deposited upon the internal surface of the substance they are to cover, in the earliest period (up to the tenth week) these corpuscles in the human subject measure from 0·000355 to 0·000405 Paris inch in diameter. They are the future pigment-corpuscles or pigment-vesicles.
