A 



k j 



■o o-^ — o 



♦ > ■• 



Figure 67. Diagrams to illustrate the method of formation of in- 

 versions, deletions and translocations. B, chromosome in the thread- 

 like condition, looped, with its two limbs in contact where they cross. 



B, the chromosome broken into three pieces at the point of crossing. 



C, inversion ; the genes f to n are reversed in their order, as a result 

 of the union in B of the region of the gene e with that of the gene 

 n, and of the region of gene / with that of gene 0. D, two thread-like 

 chromosomes in contact where they cross ; a break occurs at this 

 point. E, translocation, produced by the reunion in D of the halves 

 of one chromosome with the halves of the other. 



331 



