2OO R. S. LILLIE. 



great as possible under the conditions. Actually, however, the 

 straight form is only approximated. 



Such a filament may be caused to assume the spireme form 

 as follows : A large bar magnet is suspended vertically over 

 the filament with its north pole next the projecting south poles 

 of the needles (or vice versa] and at a suitable distance from the 

 latter. It is then found that the filament is drawn together by 

 the attraction of the magnet into a more or less regular, close 

 coil or spireme-like form, remarkably like that shown by the 

 nuclear filament in the prophase of mitosis. Briefly, the expla- 

 nation of this behavior is as follows : The filament is, by the 

 attraction of the large magnet, confined within a limited space 



FIG. I. Artificial spireme from a single filament ; the small circles indicate the 

 exact number and relative positions of the magnets. 



just as the chromatic filament in the cell is confined by the 

 nuclear membrane. Now, since mutual repulsion tends to pre- 

 vent approximation of adjacent portions of the filament, the latter 

 is forced so to dispose itself that, while occupying the greatest 

 space possible under the conditions, the average distance between 

 its adjacent portions is also as great as possible. This how- 

 ever leads inevitably to the production of the characteristic coiled 

 or roughly spiral form which is the only one that satisfies 

 these conditions, that is, in which the entire system is in equili- 

 brium. 



Figs, i and 2 are reproductions of exact drawings showing 

 the form of the artificial spireme in each of two experiments, one 

 with a single filament, the other with six separate filaments. 



