STUDIES IN GELS 



105 



capillary structure (Fig. 74a). In between these microfibrils, however, 

 interfibrillar capillaries must occur in the form of wider canals, in which 

 larger molecules such as colloid dyes and incrusting material are de- 

 posited. The porous system of ramie fibres is, therefore, heterocaplllarj ; 

 the smaller intermicellar spaces (of the order of 10 A) and the larger 

 interfibrillar ones (of the order of 100 A) communicate freely. The 





1000^ = 0.!fi 



i(ca 10 A } 

 mfca 60 J) 



Ifca 100 ^j 



b) 



o) 



Fig. 74. Miccllar structure of bast tibres 

 (from Frey-Wyssling, 1936a, 1937a). a) 

 Longitudinal and cross-section; intermicellar 

 spaces all similar (homocapillarity).Z') Cross- 

 section with coarser interfibrillar and finer 

 intermicellar spaces (heterocapillarity); 

 microfibrils f composed of micellar strands 

 m ; i intermicellar spaces, k interfibrillar 

 capillaries. 



microscopically visible fibrils must still contain both categories of 

 spaces, because. as a rule they can be dyed like the whole fibre, and 

 they thus represent aggregate bundles of the invisible submicroscopic 

 microfibrils. 



Stretching experiments. A subject which has become of special im- 

 portance in the study of gel structure is the X-ray analysis of the/)ro^(?j-j- 

 of orientation in stretching experiments. By way of example we shall 

 briefly go into the phenomena observed in stretching regenerated 

 cellulose fibres obtained from viscose. 



It is possible to make isotropic cellulose fibres from viscose 

 (Hermans and De Leeuw, 1937). The X-ray diagram of these fibres 



