An organism consists of two great groups of structural units called cells,—Germ-Cells and Body-Cells,—harmoniously associated together. As far as Evolution is concerned, the most fundamental parts of an organism are the Germ-Cells.
In order that the reader may have a working knowledge of the wonderful powers of Germ-Cells and their progeny, it is vitally important that some concrete illustrations of the activities of different kinds of cells should be given.
SECTION I.
ORGANIC CELLS: THE VISIBLE UNITS OF LIFE.
ORGANIC CELLS: THE VISIBLE UNITS OF LIFE.
In the sanctuary of S. Vitale at Ravenna, in Italy, is a very interesting representation, in mosaic pictures, and over life-size, of the Emperor Justinian and his Empress Theodora, attended by a numerous suite of ladies and courtiers. The mosaics are small bits of glass, of varying pattern and color, cemented together so nicely as to form beautiful delineations of the Emperor and his attendants.
The bits of glass or mosaics that form the figures may very appropriately be called structural units.