120 ORIGIN AND NATURE OF LIFE 



peptides, and the higher members closely 

 resemble proteins in their chemical nature. 



In the formation of the true polypeptide, 

 there is a real chemical condensation, with 

 true atomic union, and a certain amount of 

 disruptive force is necessary to achieve this. 

 In the living cell, energy obtained by oxidation 

 of other substances is utilized to do this, and 

 in the laboratory the chemist does it by having 

 present substances greedy for water. But 

 as the molecule grows in size, it will attain a 

 size at which the reverse process of disrupting 

 with uptake of water tends to occur, and a 

 position or degree of complexity will establish 

 itself at any particular environment where 

 a balance holds. In the neighbourhood of 

 this balancing point, a condition may arise 

 where two polypeptides come together, as 

 illustrated, but no atomic union can occur. 

 There is not sufficient energy to detach the 

 H and O H groups and condense. Under 

 such conditions, the two molecules may remain 

 feebly held together without true atomic 

 union as a kind of dual molecule. This 

 having occurred, the dual molecule still has 

 a free acid group and a free basic group, 

 and the acid group can enter into loose 

 molecular relationship with the basic part of 

 a third molecule, while the basic one can play 



