355 
Centrifugal Force upon the Cell. 
perhaps Vicia , the colourless area immediately surrounding 
the nucleolus is less marked than in Zea. It is certainly not 
an artefact due to shrinkage. 
The foregoing remarks pertain strictly to the nucleus in 
the so-called state of rest. A few statements may now be 
made concerning the same in process of division. 
In the stage of the hollow spirem of the anaphase, the 
chromatin-thread in vegetative nuclei runs in tolerably regular 
turns along the nuclear membrane with an occasional turn or 
loop projecting into or traversing the nuclear cavity. As the 
nucleus here considered does not increase much in size above 
that of the resting-stage, the chromatin-spirem seems toler- 
ably rigid, especially when we remember that in all pro- 
bability it is fastened at certain points to the nuclear 
membrane by delicate threads of linin or of cytoplasm. 
Nevertheless, it often happens that even in smaller nuclei of 
embryonic cells a number of turns of the spirem fall toward 
the lower side of the nucleus. 
During later stages of karyokinesis the elements of the 
mitotic figure are variously affected. The chromosomes 
when arranged in the equatorial plate are often less regularly 
oriented. The entire spindle, as in Tradescantia , falls to the 
bottom of the cell ; and, if the normal position were oblique, 
it would not infrequently be bent and sometimes forced 
to lie transversely in the cell. No very striking effects were 
observed during later phases of mitosis, save some irregularity 
in the position of the chromosomes. The resulting daughter- 
cells were often of unequal size, as in the case of the stamen 
hairs of Tradescantia. 
Seedlings of Zea^ as already stated, were allowed to grow 
after the action of centrifugal force in order to observe the 
condition of the nucleus at subsequent intervals. It required 
only a short time to recover from the shock, for at the end of 
twenty-four hours the rate of growth in the primary root 
differed but little from that of control-specimens, being some- 
times accelerated, sometimes retarded. Only few comparisons 
were made along this line as it was not my purpose to study 
