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highly specific attraction which like 

 genes (or local products formed by 

 them) show for each other. As in the 

 case of the autocatalytic forces, so 

 here the attractive forces of the gene 

 are somehow exactly adjusted so as to 

 react in relation to more material of 

 the same complicated kind. Moreover, 

 when the gene mutates, the forces be- 

 come readjusted, so that they may 

 now attract material of the new kind; 

 this shows that the attractive or synap- 

 tic property of the gene, as well as its 

 catalytic property, is not primarily de- 

 pendent on its specific structure, but 

 on some general principle of its 

 make-up, that causes whatever specific 

 structure it has to be auto-attractive 

 (and autocatalytic). 



This auto-attraction is evidently a 

 strong force, exerting an appreciable 

 effect against the non-specific mutual 

 repulsions of the chromosomes, over 

 measurable microscopic distances 

 much larger than in the case of the 

 ordinary forces of so-called cohesion, 

 adhesion and adsorption known to 

 physical science. In this sense, then, 

 the physicist has no parallel for this 

 force. There seems, however, to be no 

 way of escaping the conclusion that in 

 the last analysis it must be of the same 

 nature as these other forces which 

 cause inorganic substances to have 

 specific attractions for each other, ac- 

 cording to their chemical composition. 

 These inorganic forces, according to 

 the newer physics, depend upon the 

 arrangement and mode of motion of 

 the electrons constituting the mole- 

 cules, which set up electro-magnetic 

 fields of force of specific patterns. To 

 find the principle peculiar to the con- 

 struction of the force-field pattern of 

 genes would accordingly be requisite 

 for solving the problem of their tre- 

 mendous auto-attraction. 



Now, according to Troland (1917), 

 the growth of cr)stals from a solution 



MULLER 



is due to an attraction between the 

 solid crystal and the molecules in solu- 

 tion caused by the similarity of their 

 force field patterns, somewhat as sim- 

 ilarly shaped magnets might attract 

 each other— north to south poles— and 

 Troland maintains that essentially the 

 same mechanism must operate in the 

 autocatalysis of the hereditary par- 

 ticles. If he is right, each different 

 portion of the gene structure must- 

 like a crystal— attract to itself from 

 the protoplasm materials of a similar 

 kind, thus moulding next to the origi- 

 nal gene another structure with sim- 

 ilar parts, identically arranged, which 

 then become bound together to form 

 another gene, a replica of the first. 

 This does not solve the question of 

 what the general principle of gene 

 construction is, which permits it to 

 retain, like a crystal, these properties 

 of auto-attraction,2 but if the main 

 point is correct, that the autocatalysis 

 is an expression of specific attractions 

 between portions of the gene and sim- 

 ilar protoplasmic building blocks (de- 

 pendent on their force-field patterns), 

 it is evident that the very same forces 

 which cause the genes to grow should 

 also cause like genes to attract each 

 other, but much more strongly, since 

 here all the individual attractive forces 

 of the different parts of the gene are 

 summated. If the two phenomena are 

 thus really dependent on a common 

 principle in the make-up of the gene, 



2 It can hardly be true, as Troland in- 

 timates, that all similar fields attract each 

 other more than they do dissimilar fields, 

 otherwise all substances would be autocata- 

 lytic, and, in fact, no substances would be 

 soluble. Moreover, if the parts of a molecule 

 are in anv kind of "solid," three dimen- 

 sional formation, it would seem that those in 

 the middle would scarcely have opportunity 

 to exert the moulding effect above men- 

 tioned. It therefore appears that a special 

 manner of construction must be necessary, 

 in order that a complicated structure like a 

 gene may exert such an effect. 



