1. The R�ole of Colloids in Biological Systems -- References -- 2. Colloid Systems -- References -- 3. Colloids with Electrolytic Nature -- Antagonism of ions -- References -- 4. Complex Systems -- a) Unicomplex systems -- b) Dicomplex systems -- c) Tricomplex systems -- d) Some biological examples -- References -- 5. Association Colloids -- a) Introduction; micelle types -- b) Colloid systems of simple detergents, characterised by the presence of sandwich micelles -- c) The binding of the oppositely charged ion (The sandwich micelle regarded as a complex system) -- d) Phosphatides regarded as association colloids -- e) Suitability of phosphatides for biological purposes -- References -- 6. Elastic-Viscous Systems of Association Colloids -- a) Introduction -- b) Viscosity -- c) Elastic-viscous systems are in thermodynamic equilibrium -- d) Characteristic quantities describing the elastic properties -- e) G,? and? as a function of the oleate concentration -- f) A comparison of the elastic behaviour of elastic-viscous systems of various soaps -- g) Elastic-viscous systems of long chain electrolytes of the second and third categories (phosphatides) -- References -- 7. The Interaction between Organic Substances and Lipophilic Colloid Systems -- a) Introduction -- b) Methods -- c) The activity of aliphatic substances -- d) The activity of aromatic (and heterocyclic) substances -- e) The distribution of organic substances in the soap/salt/water system -- f) The influence of alcohols on the fixation of ions -- g) The influence of organic substances on elastic-viscous systems -- h) Biological perspectives -- References -- 8. Interaction between Long Chain Electrolytes and Proteins -- a) Introduction. The coacervation gelatin + detergent + salt -- b) The binding between protein and detergent according to the hypothesis of Pankhurst -- c) The r�ole of the salt necessary for coacervation -- d) The realisation of the coacervation gelatin + cetyltrimethyl-ammonium-bromide + salt -- e) The coacervation gelatin + oleate + K-salt -- f) Particulars of the coacervation gelatin + CTAB + KCNS -- g) Structure and composition of the detergent-rich associations -- h) The loosening effect of alcohols on the association gelatin + detergent -- References -- 9. Biological Membranes -- a) Introduction -- b) Models of the protoplasmic membrane -- c) Theoretical aspects of permeability -- d) Some experiments on the problem of the protoplasmic membrane -- References -- 10. Some Remarks on the Colloid Chemistry of Protoplasm -- a) Colloid morphology -- b) The submicroscopical structure of cytoplasm -- c) Protoplasmic flow -- References