163 
8UMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including 1 the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-Structure and Protoplasm. 
Karyokinesis in the Root-tips of Allium.*— Mr. J. H. Schaffner 
summarises as follows the main results of a careful study of the forma- 
tion of the achromatic spindle in the root-tips of Allium Cepa ; the chief 
combination of stains used being anilin-safranin and gentian-violet, 
Heidenhain’s iron-alum liaematoxylin, and anilin-safranin and iron- 
alum hEematoyxlin. 
I. Prophase. (1) The division begins with the separation of the 
centrospheres ; and when these have moved apart nearly 180°, the 
“ incept ” f of the achromatic spindle appears, forming two dome-like 
projections on opposite sides of the nucleus, at the summits of which 
the centrospheres are situated, forming the poles around which are cyto- 
plasmic radiations. At the same time the chromatin network is trans- 
formed into a continuous ribbon or spirem, producing the figure known 
as the close mother- sic ein. (2) The continuous spirem shortens and 
thickens, and is looped into a definite number of loops, the heads of 
which, in typical cases, point towards the two poles of the spindle. 
The nucleoles and nuclear membrane disappear, and the dome-shaped 
spindle becomes more pointed by the outward extension of the poles. 
This stage ends with the breaking of the chromatic loops into separate 
chromosomes, and it may appropriately be called the looped mother- 
skein. 
IT. Metaphase. (3) After the nuclear membrane disappears, the 
separate chromosomes are drawn down, with their heads towards the 
centre, into the equatorial plane, while the spindle continues to become 
more pointed. This constitutes the loose mother-skein stage. (4) When 
the chromosomes have come into the equatorial plane, there is a pause 
resulting from the seeming pull of the spindle-fibres in opposite direc- 
tions, which holds the chromosomes rigidly until their longitudinal 
splitting is complete, when separation of the daughter-chromosomes 
begins. This constitutes the mother-star stage. 
III. Anaphase. (5) After the longitudinal segmentation of the 
chromosomes, which, as a general rule, does not begin until the chromo- 
somes are in the equatorial plane, the daughter chromosomes are gradu- 
ally pulled apart, the separation beginning at the heads of the loops. 
The centrosomes usually divide during this stage, though in some cases 
the division is considerably earlier. This stage is known as metakinesis. 
(6) The daughter-chromosomes, having been completely pulled apart, 
now travel to the poles, and arrange themselves in star-shaped figures 
around the poles, while the central spindle appears between the two 
stars. The radiations around the centrospheres, which now contain two 
* Bot. Gazette, xxvi. (1898) pp. 225-38 (2 pis.). 
t Used by the author instead of “ primordium,” as the equivalent of the German 
Anlage. 
