460 
From similar facts, as are contained in table III and IV, it seems 
also possible to me, to conclude something about the rapidity from 
prophase to anaphase and from anaphase to telophase. Let us con- 
sider table III for that purpose. At 11 a.m. 2.02 °/, were in pro- 
phase and 0.38 °/, in anaphase. The number of karyokinesis figures 
in prophase has decreased with 13.8 °/, at 3 p.m. and the number 
of cell-divisions in anaphase has decreased with 44.7 °/,, so the 
decrease is intenser, that is to say, the transition from anaphase to 
telophase is quicker than the transition from prophase to anaphase. 
The same holds good for the onion in the dark during the whole 
day, but during the day an inversion takes place in such a way 
that from 6 a.m. to 12 a.m. the transition from prophase to 
anaphase is quicker than from anaphase to telophase. 
Of course these facts are too scanty to draw such far-going con- 
clusions, but the aim of this calculation was only to show that it 
is possible to learn the relative rapidity. If one wants to undertake 
such experiments it is necessary in the first place to fix the time 
of observation much shorter, i.e. one hour or one hour and a half. 
It is also possible to derive the duration of one cell-division from 
such tables. When we consider table I we do not find karyokineses 
at 8 a.m., and at 11 a.m. we find 16 nuclei in telophase. So the 
cell-division would take about 3—4 hours with Allium Cepa. JoLiy 
found with Triton the duration of the kariokynesis 2'/, hours in 
the erythrocytes at a temperature of 20° C. 
From the table of Mrs. DROOGLEEVER FortuyN—vaNn LEYDEN | think 
I may conclude the duration of a cell-division being 12 hours with a 
cat, because at 2 p.m. + 0.23°/, nuclei were in prophase and no 
telophases were stated. Only at 2 a.m. 0.20°/, nuclei were seen in 
telophase for the first time. 
When we summarize the results, we see that the roottips of the 
onion show more cell-divisions in the dark than in the light. 
Evidently light has a retaining influence. Besides it is probable 
that the transition process from prophase to anaphase is a slower 
one than the transition process from prophase to telophase. 
By lack of time I could not control these facts any further. To 
attain this, it would be necessary to make an investigation into the 
daily oscillations in the number of karyokineses with the onion, 
if possible the time of observation ought to be as long as possible 
(3 to 4 days). At the same time the above-mentioned experiment 
ought to be repeated. One onion suffices for these two experiments. 
The bulb is eut into two halves and one half is used for the first 
series of experiments and the other half voor the second experiment. 
