. General physiology; an outline of the science of life. 72 GENERAL PHYSIOLOGY as cartilage (Fig. 12). Many epithelial cells (Fig. 13, «) contain more than two nuclei; and the large ciliate infusorian, Opalina (Fig. 13, h), which lives parasitically in the intestine of the frog, contains a considerably larger number. Forms with innumerable nuclei are to be found among the marine algse: , in the thin lamellar protoplasmic layer of Caulerpa (Fig. 14), a giant cell of the shape and size of a leaf, there lies an immense number of nuclei, all of which together with the protoplasm are moving in
. General physiology; an outline of the science of life. 72 GENERAL PHYSIOLOGY as cartilage (Fig. 12). Many epithelial cells (Fig. 13, «) contain more than two nuclei; and the large ciliate infusorian, Opalina (Fig. 13, h), which lives parasitically in the intestine of the frog, contains a considerably larger number. Forms with innumerable nuclei are to be found among the marine algse: , in the thin lamellar protoplasmic layer of Caulerpa (Fig. 14), a giant cell of the shape and size of a leaf, there lies an immense number of nuclei, all of which together with the protoplasm are moving in a constant slow stream between the cell-walls, , the two surfaces of the leaf All these organisms containing several nuclei can be separated as multinucleate cells from multicellular tissues by the fact that in the former the protoplasmic territory immediately surrounding the individual nuclei is not sharply defined from the neighbouring protoplasm, but together with all the rest of the protoplasm con- stitutes a unitar}^ mass which appears as a whole shut off from the. Fig. 13.—a. Epithelium-cell, containiug several nuclei from the uriuary bladder of man. (After Virchow.) h, Opalina ranarum, a unicellular ciliate infusorian, containing many nuclei, from the intestine of a frog. (After Zeller.) outside by a definite surface, while in the tissue every individual protoplasmic territory which belongs to a nucleus is sharph- separated from all the rest. The multinucleate cell, therefore, represents one cell, which is characterised as a whole bv a definite form of surface; the tissue, however, consists of a sum of single cells, each one of which has its own sharplj^ defined form. The distinction between multinucleate cells and genuine tissues becomes more difficult in the case of certain low organisms, the Myxomycetes, which have frequently been claimed by the botanists as plants and by the zoologists as animals, and which in man-\- respects are of great interest. They are so
Size: 2037px × 1227px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookauthorverwornmax18631921, bookcentury1800, bookdecade1890
