ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
583 
Behaviour of the Nucleoles during Karyokinesis.* * * § — Dr. A.Zimmer- 
mann records the results of observations which tend to contradict the 
prevalent view that the nucleoles are entirely absorbed during karyo- 
ldnesis, arising again in the daughter-nuclei after metakinesis. The 
observations were made on anthers of Lilium Martagon and Hyacinthus 
candicans, sporanges of Eqnisetum palustre and Psilotum triquetrum , 
embryo-sac and nucellus of Lilium Martagon , endosperm of Fritillaria 
imperialis, apex of the root of Vida Faba , apex of the stem of Pliaseolus 
communis and Psilotum triquetrum. The material was fixed by Merkel’s 
compound and imbedded in paraffin, the sections were stained by a 
mixture of iodine-green and fuchsin, washed with alcohol containing 
1 gr. iodine and 1 cm. acetic acid to 100 cm., the alcohol removed by 
xylol, and this replaced by Canada balsam. The nucleoles are by this 
process coloured a deep red, the chromatin globules a deep green or blue 
or even blue-violet, the cytoplasm remaining colourless or light red. 
It was thus demonstrated that bodies appear in the cytoplasm during 
karyokinesis identical with the nucleoles of the resting nucleus. They 
are wanting immediately before karyokinesis, and are without doubt the 
product of the breaking up of the nucleoles. Subsequently these extra- 
nuclear nucleoles disappear from the cytoplasm, and appear to wander 
back to the daughter-nuclei, where they coalesce to form the large 
nucleoles. 
These observations appear to negative the hypothesis of a sharp 
demarcation between the nucleus and the cytoplasm in all stages of 
karyokinesis. Elaioplasts were detected in the parenchyme-cells of 
Psilotum. 
Nucleoles and Centrosomes.f — Prof. J. E. Humphrey asserts that 
the phenomenon, observed by Strasburger and Zimmermann, of the 
presence of nucleolar substance in the cytoplasm which has been ex- 
pelled from the nucleus during cell-division, is not universal, and is 
only of exceptional occurrence. The author’s observations were made 
on mother-cells of pollen and spores, cells from the apex of the root, and 
the parietal layer of the embryo-sac. The nucleoles he regards, not as 
a store of reserve-material for the nucleus, but as passive structures, 
the number, form, and size of which depend on the activity of certain 
forces within the cell. The vacuoles of the nucleoles are the natural 
result of the subsequent separation of the more fluid from the more solid 
portions of the nucleolar substance. The bodies known as “para- 
nucleoles ” are probably artificial products of the action of the 4 x i n g 
material. The body described by Karsten J as the “ nucleo-centrosome ” 
is shown, by its reaction with staining reagents, not to be a true centro- 
sphere, but a portion of chromatin. Nucleoles and centrosomes are 
perfectly distinct substances, having no relation to one another. 
Chemistry of the Cell- wall. § — Pursuing his observations on this 
subject, Herr E. Schulze replies to various objections of Gilson against 
* Beitr. z. Morph, u. Phys. d. Pflanzenzelle (Zimmermann), ii. (1893) pp. 1-35 
(2 pis.). 
f Ber. Deutscli. Bot. Gesell., xii. (1894) pp. 108-17 (1 pi.), and Ann. Bot., viii. 
(1894) pp. 373-6. J Of. this Journal, ante , p. 360. 
§ Zeitschr. f. Phys. Chemie, xix. pp. 38-69. See Bot. Centralbl., lviii. (1894) 
p. 209. Of. this Journal, ante , pp. 215, 216. 
