Inversion 



399 



will appear more or less normal except for the fragments. One 

 fragment may be found in each cell or there may be two in one 

 and none in the other. Other anaphase configurations may be 



=1= 



3 



I 



i 



I 



I 



abed 



Fig. 105. Configurations at Anaphase I (first row) and Anaphase II 

 (second row) following crossing over within the inversion diagrammed 

 above, (a) Configurations following a crossover at 1 or 2 in the inversion. 

 (h) Those following crossovers at both 1 and 2, both within the inverted 

 segment, (c) Configurations following crossovers at 2 and 3. (d) Those 

 following crossovers at 1, 2, and 3. (Courtesy of Dr. B. McClintock in 

 Research Bulletin 290 of the University of Missouri Agricultural Experi- 

 ment Station.) 



found if there is a crossover between the inversion loop and 

 the centromere as well as within the inversion. Dicentric chro- 

 mosomes and chromatid bridges arise spontaneously and have 

 been induced by X-rays (Fig. 107). 



