. The plant, an illustration of the organic life of the animal. Biology. COMPAEED WITH THOSE OF ANIMALS. 53 applied by Swann to the tissues of animals, are now ad- mitted by almost all physiologists, the following abridg- ment of them will be acceptable :— When there are the appropriate external conditions, the first visible stage of cell-formation consists in the appear- ance of minut,e granules which trouble the clear gummy solution in the cells, or the interspaces which surround them, rendering it turbid and opaque. Some of these granules collect together and form a nucleus around which oth
. The plant, an illustration of the organic life of the animal. Biology. COMPAEED WITH THOSE OF ANIMALS. 53 applied by Swann to the tissues of animals, are now ad- mitted by almost all physiologists, the following abridg- ment of them will be acceptable :— When there are the appropriate external conditions, the first visible stage of cell-formation consists in the appear- ance of minut,e granules which trouble the clear gummy solution in the cells, or the interspaces which surround them, rendering it turbid and opaque. Some of these granules collect together and form a nucleus around which other granules (nucleoli) gather, so that they ultimately acquire a larger size than the rest. These nucleated agglo- merations, called by Schleiden, cytoblasts, become each an . active centre around which the mucilaginous fluid of the protoplasm organizes itself. As soon as the cytoblasts are fully grown, a fine transparent vesicle developes on one side of them. This vesicle first appears as the segment of Pig. Cells of a leek, after Quekett. a, nucleus; &, nucleolus. a sphere, the cytoblast forming its flat side and the walls of the vesicle its convex surface. The vesicle continues to expand until at length the cytoblast from which it ori- 5*. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coultas, Harland, d. 1877. Philadelphia ; Perry and Erety
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