ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
65 
animal cells.* The two bodies gradually approach one another at the 
apex of the nucleus, and fuse together into a single large body, which is 
at first in close contact with the nucleus, but subsequently makes its 
way to the top of the basid, followed by the nucleus, which then begins 
to divide. While the chromatic elements are being developed, the 
centrosphere undergoes a change. It is at first in close contact with 
the nuclear threads as a homogeneous mass more or less spherical in 
outline, which gradually becomes more irregular, and finally disappears. 
Shortly after this the spindle-figure appears, with the two centrosomes,. 
one at each end ; the spindle being probably formed out of the substance 
of the archoplasmic body as it becomes invisible. The archoplasmic 
bodies are first seen in the basid at the stage when it contains two large 
nuclei formed by the fusion of four pre-existing nuclei. 
Karyokinesis. — Herr W. Belajefff finds the pollen-mother-cells of 
Larix , especially of L. davurica , a very favourable object for following 
out the various stages of the division of the nucleus, for which they are 
in a condition during the period of winter repose. The preparations 
were fixed by Flemming’s solution, and stained first with saffranin and 
then with gentian- violet or orange G. 
When cell-division commences, the first change which takes place 
is the formation round the nucleus of a dense felted layer composed 
of meshes parallel to the wall of the nucleus. In the meantime the 
chromatin-granules contained in the nucleus coalesce into homogeneous 
irregular chromatin-bodies, usually X -shaped, or angular with four pro- 
jections. The outer felted layer and the inner mass of threads form 
together a central body sharply differentiated from the surrounding proto- 
plasm, within which lie the chromatin segments. After the absorption of 
the wall of the nucleus, the nucleole gradually disappears. The threads 
of the protoplasm form at this time irregular knots, but gradually unite 
into groups. The further changes in these filaments are followed in 
detail. During these processes the chromatin segments are gradually 
constituting themselves into the equatorial group. Every new segment 
of the nucleus originating in each polar half has the form of a bow 
which is fixed at its middle to the filament-bundle, the free ends facing 
the equatorial plane of the spindle. 
The division of the pollen-mother-cells of Lilium and Fritillaria 
proceeds in a course which, in its main features, is identical with that of 
Larix. 
Herr R. FranzeJ describes the karyokinetic processes which take 
place in the division of the nucleus after the conjugation of swarmspores 
in Algae. 
Origin of the Directing Spheres.§ — M. L. Guignard contests the 
view of Karsten || that the centrosomes have their origin in the nu- 
cleoles ; he re-affirms his previous statement that these bodies are always 
* Cf. this Journal, 1894, p. (566. 
+ Flora, lxxix. (1894) Erganzungsbd., pp. 430-42 (2 pis.). 
x SB. K. Ungar. Naturw. Gesell. Buda-Pest, March 14, 1894. See Bot. Cen- 
tralhl., lix. (1894) p. 267. 
§ Journ. de Bot. (Morot), viii. (1894) pp. 241-9, 257-64 r (l pi.); Comptes 
Rendus, cxix. (1894) pp. 300-2. Cf. this Journal, 1891, p. 614. 
11 Cf. this Journal, 1894, p. 360. 
1895 
F 
