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536 DENTAL EMBRYOLOGY AND HLSTOLOGY.
Fig In some of the cold-blooded animals the palate
is covered with ciliated cells. These are for the
most part spheroidal in form, and do not differ
greatly from the cells above described. The most
remarkable circumstance in connection with them
is the movements of their cilia, which arise from
the broad side of the cell. These hair-like append-
ages are supposed to be prolongations of the cell-
Columnar Ciliated i:\n- protoplasm. They can be seen in the frog, and ex-
thelium Cells.
amined while yet in motion by scraping the surface
Fig. 274.

/?• ^'^^a^ -^—^ ^^

Epitheliuin-cells of Snlatnander Larva in Dift'erent Thases of Pivision : a, normal cell, by con)pari-
son with which the following changes may lie noted : I. The network of filaments of the resting
nucleus becomes formed into a sort of xkein, formed apparently of one long coiivoluted filament;
the nuclear membrane and the nucleoli disappear or are merged into the skein (/<. c, rfi. II. The
skein becomes arranged in the form of a ri/xr/fi', the filaments looping in and out to and from the
centre ('-). Ill The outer loojjs of the rosette separate so that the filament breaks into a lum-
ber of V-shaped fibres arran-ed like a star {(i.ttfr./, g, /i). IV. The V-shaped fibres separate into
two groups, the ends of which are for a time interlocked (/,./. k). V. The two groups pass to the
opposite poles of the now elongated nucleus and form a star-shaped figure /) at each pole ulynsli-r).
Each of the stars represents a daughter-nucleus. VI. Each star of the d vaster i;oes through the
same changes as the original nucleiis, but in the reverse order— viz. rosette im). skein (??), and net-
work (fi, p, 91— passing finally into the condition of a lypal resting nucleus. The jirotoplasm of
the r-ell divides soon after the formation of the dyaster (/;/ 1. Sometimes fine lines may be seen in
the i>rotoplasm, during the i>rocess of division, radiating from the poles cf the nucleus, and others
uniting the two daughter-nuclei.