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In my opinion, it is this rotating action which brings about 
the appearances which have been mistaken for spiral vessels. 
The explanation which I have to offer for the phenomenon 
is this : first, we have the external membrane of the cotton, 
then the cellulose and primordial utricle, and finally, the 
dried contents in the cell, which I take to be the remains of 
the organising fluid. 
Observation shows that the external membrane is not 
elastic and only partially soluble. 
The cellulose is exceedingly elastic and soluble, and ex- 
pands to a remarkable degree in the act of dissolution. The 
contents of the cell behave in a similar manner to that of the 
external membrane; it is neither elastic nor very soluble. 
The most successful experiment is made by allowing the 
copper solvent to come at once into contact with some length 
of the cotton hair. The solvent permeates some parts of the 
external membrane more easily than others, and causes a 
rapid expansion of the cellulose, which bursts the external 
membrane, and as this action is taking place at various por- 
tions of the same hair, a tangential force is exerted which 
twists and contorts the cotton in the direction of its length, 
and thus a spiral appearance is given to the whole structure 
of the cell. 
The non-elastic external covering is twisted round the 
expanded cellulose, sometimes as a single band, at others 
like a bundle of fibres. 
In those parts where the external covering has given way 
all round the hair, the cellulose expands into a bulb, pushing 
back the external membrane into a series of folds which form 
a ligature, and resists the expansive force of the cellulose. A 
number of these ligatures cause the expanded cellulose to 
assume the appearance of a string of beads. The lateral 
expansion of the cellulose contracts the length of the hair, 
and this causes the contents in the cavity of the cell to 
assume a corrugated appearance ; this corrugation has also 
