I 



CYTOPLASM 169 



lower than the values for many true viscous liquids (Table XXII). 

 For a true liquid should in the first place be homogeneous in the 

 physical sense and this certainly does not apply to cytoplasm. The 

 following comparison may be permitted : 



Consider a wad of thread-like algae. The threads can be moved at 



TABLE XXII 

 RELATIVE VISCOSITY fj 



Water * i 



Cel/ sap.- 

 Stem parenchyma, oi the Vida Faba seedlinp: ... 1.9 (Heilbronn, 1914) 



Protonemz of Lepiobrjum piriforwe 1.9 (Pekarek, 1933) 



Epidermic cells of the .^///«w (7f/>a bulb 2 (Pekarek, 1930) 



Terminal vacuole of C/i9.r/cr///w (see Fig. 1 1 2a, p. 192) 2.5 (Frey, 1926c) 



Cytoplasm : 



Amoeba 6 (Pekarek, 1930) 



Stem parenchyma of the Vicia Faba^eeAhne. ... 24 (Heilbronn, 19 14) 

 Red cell of man 30 (Ponder, 1934, p. 87) 



Viscous liquids: 



Glycerol 87 (L.a.ndolt-B6rnstein, 1923) 



Paraffin oil 92 ,, 



Castor oil 1250 ,, 



wiU with respect to each other, although they impede each other's 

 freedom of movements as a result of their extremely anisodiametric 

 shape. When transferring this microscopic model to the molecular 

 domain, the threads become long chain molecules in a dispersing 

 medium and a drop of this macromolecular sol would show structural 

 viscosity and all the capillary phenomena described. If the individu- 

 alized algae threads of our model were replaced by the graceful 

 reticular alga Hydrodictyon (Oltmanns, 1922, p. 277), scarcely any 

 change in the inner mobility of such a wad of algae would be observed. 

 On a molecular scale this means that a drop which contains a coherent 

 three-dimensional molecular network, instead of free chain molecules, 

 will not only assume a spherical shape but also show a constant 

 contact angle and spread on the surface of suitable liquids. In spite 

 of this, the structural elements of the network cannot move freely! 

 The network is so flexible, however, that its shape within the drop 

 is determined by the forces of surface tension. /Ul the same, we cannot 



