. The cell; outlines of general anatomy and physiology. ally undergoing the process, are so stronglystained that they cannot fail to attract the attention of theobserver. Daring- the first stage of coil formation the nucleoli are stillpresent; however, they gradually diminish in size, until after ashort time no trace of them can be seen. Up till now it has notbeen determined with certainty what is formed from them. Whilst the coil is developing, careful observation reveals a smallspot on the surface of the nucleus. This becomes more and moredistinctly defined as the process progresses : it has
. The cell; outlines of general anatomy and physiology. ally undergoing the process, are so stronglystained that they cannot fail to attract the attention of theobserver. Daring- the first stage of coil formation the nucleoli are stillpresent; however, they gradually diminish in size, until after ashort time no trace of them can be seen. Up till now it has notbeen determined with certainty what is formed from them. Whilst the coil is developing, careful observation reveals a smallspot on the surface of the nucleus. This becomes more and moredistinctly defined as the process progresses : it has been designatedby R-abl the polar area (Fig. 77). The opposite surface of the nucleus is the anti-polar area. Thenuclein threads become graduallymore and more distinct, and ar-range themselves so as to pointtowards these two areas. Starting from the anti-polarregion they collect in the neigh-bourhood of the polar area. Herethey bend round upon themselvesin a loop-like fashion, and thenreturn, by means of several small,irregular indented loops, to the. Fig. 77.—Diagrammatic representa-tion of a nucleus with a polar area, inwhich the two centrosomes and thespindle are developing. (After Flem-ming, PI. 39, Fig. 37.) neighbourhood of their starting point. Later on the threads be-come shorter and correspondingly thicker; they are less twisted,and cling less closely together, so that the whole skein looks muchlooser. In the meantime their arrangement in loops graduallygrows more and more distinct. In favourable cases it has beenascertained that there are twenty-four such loops or nuclearsegments ; this number is constant for the tissue cells and sperm-mother-cells of Salamandra and Triton. Meanwhile the two centrosomes and the spindle — most im- THE VITAL PHENOMENA OF THE CELL 185 portant portions of the nuclear figure—have developed in thepolar area. However, on account of the difficulty in stainingthem, and their minute size and extreme delicacy, these appearancesare not eas
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