270 CHROMOSOMES IN HEREDITY: MECHANICAL 



Fig. 92. — The results of crossing-over in inversions in Chorthippiis. 

 a, pachytene pairing, h, diplotene bivalent which has single 

 crossing-over between two relatively inverted and translocated 

 segments, giving an acentric and ring chromatid, c, d, first 

 anaphase and telophase with bridge and fragment {X chromo- 

 some also solid), e, first division bridge surviving at second 

 telophase. /, second division bridge {M chromosome) with 

 fragment left in sister cell. X ca. 2000 (D., 1936 d). 



the acentric fragment by the sum of the lengths of chromosome 

 distal to it and less than that of the bridge by the sum of the lengths 

 of chromosome proximal to it. Further the relative lengths of 



