112 CELL HEREDITY 



by correlating observations from the very different disciplines of genetics 

 and cytology. The segregation and recombination of genes were found 

 to be governed by the mechanics of chromosome behavior, whether 

 normal or aberrant. The recombination of linked genes, attributed to 

 the process of crossing over, was shown to exhibit certain regularities: 

 recombination at the four-strand stage, reciprocal recombination in each 

 individual meiosis, correlation of recombination frequency with chiasma 

 frequency, positive chiasma interference. These regularities, generalized 

 as the partial chiasmatype theory, are characteristically found in studies 

 of linked genes, several map units apart, undergoing recombination 

 during meiosis. 



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Belling, J., 1933. Crossing over and gene rearrangement in flowering plants. 



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 Creighton, H. B., and B. McClintock, 1931. A correlation of cytological and 



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