ties of the living organism. As will be seen later, the 

 polypeptide spiral which probably constitutes the ulti- 

 mate unit of living matter measures only about 5 Ang- 

 strom units in width, whereas the nuclei of the cells of 

 the higher animals are about 3000 times larger. A single 

 germ-cell of one of the higher animals may therefore 

 contain many thousands of polypeptide spirals. If now 

 we assume that each spiral can be attached to the one 

 immediately preceding it in either of two different ways, 

 then the number of ditferent patterns which would be 

 theoretically possible would be 2 multiplied by itself 

 thousands of times — and this represents only that por- 

 tion of one's makeup which is inherited. The real com- 

 plexities do not begin until this inherited pattern is elab- 

 orated in millions of different varieties in the cells of 

 the cerebral cortex. Let no one say that the mechanistic 

 conception of life is inadequate to account for the rich- 

 ness of variety in our conscious experience. 



The polypeptide system of protein chemical structure, 

 (and also the diketopiperazine system, as will be ex- 

 plained later,) will readily adapt itself to the above-men- 

 tioned geometric theory of heredity. By arranging a 

 number of polypeptide chains in parallelism, and connect- 

 ing them to one another through side-chains, we can pro- 

 duce structures having any desired pattern in cross-sec- 

 tion, but with the longitudinal dimension remaining avail- 

 able for the perpetuation of this pattern by endwise 

 growth of the polypeptide chains. In reality these poly- 

 peptide chains are probably not rectilinear but in the 

 form of helical spirals with six atoms to a convolution. 

 Such a spiral structure would also account for the optical 

 activity (rotation of the plane of polarization of light) 

 which is always exhibited by amino acids obtained from 

 natural sources. 



The parallelism of the polypeptide chains in naturally 

 occurring fibrous proteins (silk fibroin, keratin, myosin. 



