II. THE NATURE OF GENES 239 



lized structures governing each of their differentiated and complicated 

 characters would be arranged the more orderly in the protein mole- 

 cules constituting genes. 



The protein components in the nucleoprotein in the nucleus were 

 believed to be basic proteins, such as histone and protamine, but at 

 present a series of workers claim that the chief protein in the chro- 

 mosomes is acidic one named chromosomin as already stated in Part 

 11. In general, protoplasm consists of protein of globulin nature, which 

 is also of acidic nature, and hence chromosomin may be a protein of 

 globulin nature, forming genes by combining with nucleic acid, whose 

 threads are presumably oriented parallel to the protein threads (18). 

 Stedman (19) who was the first to find that the main protein compo- 

 nent of chromosomes is acidic protein, objects to the opinion concerning 

 the importance of nucleoprotamines and nucleohistones in heredity, 

 because the structure of protamines is so simple that it could hardly 

 account for their alleged importance as carriers of heredity. 



In short, all the characters of organisms are subjected to the 

 structures of protoplasm protein, which in turn are governed by the 

 structure of genes. In the gene of higher organisms of most compli- 

 cated characters, there must be present a great number of localized 

 strong structures each of which may direct each component factor of 

 the complicated characters ; and a single gene may have only a single 

 localized structure so that the number of genes may be equal to that 

 of localized structures. If there are two genes which govern the 

 structure of the same portion, the structure of the portion should be 

 determined by the stronger gene, thus the reason why there are do- 

 minant and recessive genes may be readily explained ; this must of 

 course be an interference phenomenon between genes. 



This concept is elucidated in Fig. 23, in which structures of the 

 restricted portions are shown by various patterns ; those given by 

 dotted lines are weak structures, which are subjected to the strong 

 patterns of non-dotted lines. Each gene in a pair is inherited from 

 each of the parent and the structure of the restricted portion is 

 determined by the stronger one, the dominant gene, which accordingly 

 directs the character subjected to the structure. 



Genes are, therefore, virus-like polymerization products of proteins, 

 a portion of which is endowed with a particularly strong structure. 

 Each of a certain number of the particles which are comparatively 

 similar to one another may aggregate into each larger body at a 

 stage of the cell division ; such aggregates may be termed chro- 

 mosomes. Since different genes sharing the site of determination 

 in common may repel each other, each gene in a pair may be distri- 

 buted to different chromosomes so that every gene in a chromosome 



