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VEGETABLE CELLS.

I will here mention another phenomenon which I ob-served a few times. I do not think that Schleiden hasallowed himself to be deceived by this ; yet others, whomay also observe it, may easily suppose it to be the processof cell-formation as described by Schleiden , to which itbears great resemblance. Nuclei which have attained aconsiderable size, absorb water by endosmose. Themembrane of the nucleus detaches itself on one side fromthe contents, the interspace becoming filled with water.The comparison with a watch-glass is here not inapt. Insome cases, the membrane continues to expand, suddenlybursts, and disappears. In others, this expansion goeson to a variable extent, and ceases when the force of the *endosmose and the elasticity of the membrane come intoequilibrium. The membrane remains visible and is notdissolved. (See fig. 9, i, k, l, m ; in h, i, k the same nu-cleus is represented previous to the action of the water,and in two stages after the operation of endosmose hasbegun.)

If the nuclei contain only one nucleolus, one mayreadily suppose them to be cells, and the hollow spaceround the nucleolus to be the nuclear vesicle (fig. 9, i, k).Those forms, with two or three nucleoli (fig. 9, /), how-ever, prove that it is inside the nuclei that the hollowspaces have been formed through the action of water, asis the case in the nucleus represented in fig. 9, c-g. Thecontents of the nucleus are pretty sharply defined wherethey join the water. The' outer circumference of thenucleus exhibits a dark line, which is formed by the de-licate membrane lying close upon the contents, and which,therefore, is lost when this membrane has become detachedfrom the contents (fig. 9, k, l, o). These facts furnish anew proof that the nuclei possess a membrane and arevesicles.

The young cell appears at first as a layer of mucilagesurrounding the nucleus. Subsequently a membranebecomes visible on the surface of the mucilage. Conse-quently the cell is at first, besides the nucleus, quite filled