562 “Dr. Mi artog, [ Dec. 1, 
scarcely more than molecular value.* If we place in a solution of a substance 
a erystal of the substance dissolved, this will determine a flow of liquid 
towards itself, and may be termed “ positive”; if we introduce a droplet of 
the solvent, it will act as a centre of repulsion, or “negative” pole. If we 
take a solution of saltpetre, and introduce into it a crystal of this substance, 
and, at a distance, a droplet of defibrinated blood—of lower isotonic value 
than the solution—the blood-corpuscles may be seen to flow along the curves 
of a spindle to the crystal. Two “like” centres, whether of concentration or 
of dilution, always behave as “like” poles, and determine the “crossed 
field”; consequently this group of phenomena cannot determine the cell-field. 
I should say frankly that Leduc’s experiments were undertaken in the hope 
of applying the explanation of diffusion to mitokinetic force; so far as I 
know, he still retains the belief that it can be done.t 
Biitschli has described and photographedt alleged “spindles” in films of 
jelly cooled and dried on glass, around air bubbles, thus converting the 
alveolar structure of the jelly, which he has done so much to elucidate, into 
a radial structure. Now, on this argument, a posteriori, we may note :— 
(1) His figures appear in his plates absolutely ambiguous, the rays of some 
of the spindles meeting at an angle on the equator, as if the medium were not 
permeable, and the far pole had no inductive effect. (2) The centres, as 
figured in the less ambiguous cases, are not such as to carry the conviction 
that they are “like” members of a pair, and, though the differences 
may be due to differences of level and focus, it is rather significant that 
Biitschli does not notice their unlikeness, or think it needful to comment on 
it. (3) The discussion in the text is wholly inadequate, showing clearly how 
far the author has failed to realise the physical difficulties in the way of his 
views. I may translate, in illustration of this physical inadequacy, the opening 
passage, describing the asters, and leading up to the spindles: “The tension 
exerted in all directions by the decreasing size of air-bubbles on the 
surrounding alveolar network must, of course, decrease in the inverse ratio 
of the square of the distance. The decrease of the visible action of this 
* “Champs de Force de Diffusion,” ‘Comptes Rendus Assoc. France,’ Montauban, 1902, 
p- 809; “Les Champs de Force chez les Etres vivants,” ‘Comptes Rendus Soe. Biol.,’ 
vol. 4, p. 367, 1903. 
+ [Leduc has now recognised that the centres in the dividing cell are “ like” centres in 
respect of diffusion, and explains the cell-spindle as a false-spindle, ‘C. R.,’ December 5, 
1904: this explanation is irreconcileable with the existence of continuous spindle fibres 
extending in the cell from pole to pole across the equator.—Note added during the 
printing. | 
t “Untersuchungen iiber Strukturen, insbesondere iiber Strukturen nichtzelliger 
Erzeugnisse des Organismus, und iiber ihre Beziehung zu Strukturen welche ausserhalb 
des Organismus entstehen,” 1898. 
