
1904. ] The Dual Force of the Dividing Cell. 563 
force in the transformation of the alveolar into a radiate structure must, 
however, since it involves relations of volume, take place in the inverse ratio 
of the cube of the distance.”* We know nothing of forces acting “ inversely 
as the cube of the distance,’ and I cannot see why Biitschli should have 
thought it necessary to assume such. 
Rhumbler, who also believes that the action of surface-tension and diffusion 
on the alveoli of Biitschli produces the cell-figure, has devised an ingenious 
model to illustrate the action of the forces at the centres.| He forms a net, 
of some 300 india-rubber rings each united to its neighbours by six bonds to 
form a hexagon; the net is approximately circular, and some 20 meshes 
across. ‘This is stretched on an iron hoop over a sheet of cardboard or paper 
in which holes are pierced. Through these holes the net can be drawn down 
to represent centres of radial attraction. If two such centres be taken and 
the net pulled through both, the intervening meshes along the intercentral 
axis are pulled out and narrowed, the narrowing being extreme at the 
poles, and least half-way between them. He interprets the widening of 
the central row of meshes towards the equator as showing that under these 
conditions two undifferentiated or “like” forces can produce a “spindle” 
field. 
I confess that I was not a little puzzled by this apparent contradiction of 
mechanical principles. However, on looking at the net, we find that the 
so-called “spindle” arrangement involves about eight meshes in length and 
ceases completely within two meshes on either side of the centre; and that 
the long sides of all the remaining meshes form broken curves, which, with a 
minimum of smoothing out, clearly follow the lines of the “crossed field” 
just as might have been anticipated. The apparent “spindle” is a mere grain- 
or texture-result, due to the large size and inadequate number of the meshes. 
Had he made this net of 2700 meshes, so as to have a diameter of 
nearly 60 meshes, and put his centres 24 meshes apart, he would have seen 
that the “spindle” was no wider than before. Yet even with this enlarge- 
ment the number of meshes in the intercentral “ spindle” would have been of 
a much lower order of number than the Biitschlian alveoli in the spindle of a 
dividing cell; while the cell-spindle is much wider relatively to its length. 
* “Die Zugkraft, welche bei der Verkleinerung der Luftblasen allseitig auf das 
umgebende Wabengeriiste wirkt, muss natiirlich umgekehrt proportional dem Quadrat 
der Entfernung abnehmen. Die Abnahme der sichtbaren Wirkung dieser Kraft, welche 
sich in der Umformung des Wabengeriistes zu strabliger Beschatfenheit aussert, nimmt 
dagegen wohl, da es sich um koérperlichen Verhaltnisse handelt. umgekehrt der 3 Potenz 
der Entfernung ab,” p. 158. 
t “Versuch einer Mechanische Erklarung der indirekten Zelltheilung: 1 Th. Die 
Cytokinese,” ‘ Arch. Entw.,’ vol. 3, 1896. 
VOL. LXXVL—B. 2 Q 
