Embryology. 129 
I will quote the following description of them, because, 
for terseness combined with lucidity, it is unsur- 
passable. 
Researches, chiefly due to Flemming, have shown that the 
nucleus m very many tissues of higher plants and animals con- 
sists of a capsule containing a plasma of “ achromatin,” not deeply 
Fic. 36.—Karyokinesis of a typical tissue-cell (epithelium of Sala- 
mancer). (After Flemming and Klein.) The series from A to I 
represents the successive stages in the movement of the chromatin 
fibres during division, excepting G, which represents the ‘nucleus- 
spindle” of an egg-cell. A, resting nucleus; D, wreath-form; E, 
single star, the loops of the wreath being broken; F, separation of 
the star into two groups of U-shaped fibres; H, diaster or double 
star; I, completion of the cell-division and formation of two resting 
nuclei. In G the chromatin fibres are marked a, and correspond to 
the ‘equatorial plate”; 4, achromatin fibres forming the nucleus- 
spindle; ¢, granules of the cell-protoplasm forming a “polar star.” 
Such a polar star is seen at each end of the nucleus-spindle, and is 
not to be confused with the diaster H, the two ends of which are 
composed of chromatin. 
stained by re-agents, ramifying in which is a reticulum of “ chro- 
matin” consisting of fibres which readily take a deep stain. 
\Fig. 36, A). Further it is demonstrated that, when the cell is 
about to divide into two, definite and very remarkable move- 
ments take place in the nucleus, resulting in the disappearance 
of the capsule and in the arrangement of its fibres first in the 
x K 
