4 STUDIES IN GELS 105 



the order of magnitude 10 A which are responsible for the phenomena 

 of swelling, and 2. wider capillary spaces which are accessible to dyes 

 of much larger dimensions and to the hardening substances Hgnin, 

 cutin, etc. For this reason they are of primary importance technically 

 in the process of dyeing and physiologically in the hardening of the 

 cell wall. It must be supposed that these larger spaces are widened by 

 the growth of the substances embedded. 



The capillary shape of the wider spaces can be proved in the follow- 

 ing way: in objects with a well-developed fibre texture the gold and 

 silver particles embedded give rise to a strong rodlet dichroism 

 (Frey-Wyssling and Walchli, 1946). This is only possible if the 

 isodiametric metal crystals are arranged in rows or in rod-shaped 

 aggregates; i.e., the metal particles must lie in pre-formed submicro- 

 scopic canals. Even more can be inferred from experiments with 

 silver amalgam. If mercury is precipitated in the fibre from an alcoholic 

 solution of sublimate, dichroic colouring is obtained which does not 

 produce an X-ray diagram, because the mercury is present in the Uquid 



Fig. 7 1 . Oriented embedding of silver amalgam in the fibre. In addition 

 to the fibre diagram of cellulose (broad interference spots) a fibre dia- 

 gram of silver amalgam (narrow interference spots)appears (frompREY- 



Wyssling, 1937a). 



state. Treating the fibres afterwards with a solution of silver nitrate, 

 one obtains X-ray diagrams showing interferences of silver amalgam 

 (Fig. 71) in addition to the diagram of cellulose. The silver amalgam 



