302 PHYSIOLOGICAL GENETICS 



arginine. As a model, she takes the clupeine. It is said to 



consist of Ions chain molecules, in which arginine residues 

 alternate with certain nionoaminoacid residues, 4 or 5 of the 

 former to 2 of the latter, altogether 28 residues, with the length 

 of the chain 98A. Such molecules, placed end to end and held 

 together by suitable bonds in a chain, form the protein pattern 

 of the chromosome, and a bundle of these constitutes a chromo- 

 some micella. The individual molecules are different poly- 

 peptids, and the pattern may therefore be expressed in terms of 

 side chains of the constituent molecule. The bundle, the 

 micella, may have any width without changing this pattern. 

 Any difference in this pattern, be it of one residue (estimated 

 length 3.5A.) or of one molecule (98A.), would constitute a 

 genetical difference. Wrinch points here to the position effect, 

 which would fit into such a picture. A calculation shows that 

 such a pattern of chromosome length may vary to the number of 

 2Q5o,ooo patterns. Wrinch then proceeds to find the proper place 

 for the nucleic acid, also present in the chromosome. She views 

 the constitution of this molecule as possessing four negatively 

 ionized centers, which are bound to form basic compounds with 

 the positive amino acid residues. If all four centers do this, and 

 if, as assumed above, all the chains within the micella are identi- 

 cal, the nucleic acid ions will completely encircle the micella. 

 This is the reason why the protein molecules aggregate : they are 

 held together by these nucleic acid ions. This relation may also 

 be expressed by comparing the protein pattern to the warp 

 and the nucleic acid to the woof of a fabric. It may be added 

 that if the nucleic acid molecule is highly polymerized, it may 

 hold together, instead of four, a large number of parallel protein 

 molecules. 



In harmony with this concept of the chromosome, Wrinch 

 assumes that a gene is a group of molecules between the natural 

 breakage points, viz., the bonds between the individual chains of 

 molecules. We shall return later to this hypothesis which may 

 also be adapted to a very different point of view. 



B. Friesen's Hypothesis of Chain Mutation 



In an earlier chapter we mentioned the hypothesis of Dubinin 

 (page 296) that the gene is composed of subgenes, or centers, 

 which mutate independently; the mutated gene is the sum of 



