BEHAVIOUR OF FRAGMENTS 



M3 



studied at meiosis in many of them (Table 17). It has the following 

 characteristics. 



(a) In an organism with negligible terminahsation in the major 

 chromosomes, the fragments are always associated terminally (e.g., 

 Fntillaria and Lilium). Thus three homologous fragments may 



Fig, 48. — Mitotic metaphase in polar view in a clone of Fritillaria 

 imperialis with six fragments {2n = 24 + 6ff). These are 

 probably present along with the unfragmented sister chromo- 

 somes of those from which they are derived and are therefore 

 reduplications. The chromosomes have been spread out in 

 drawing ; those with median centric constriction are marked M, 

 Cf. Fig. 95. X 2200 (from D., 1930 c). 



form a triple chiasma before diakinesis. This indicates that slight 

 movement of chiasmata occurs, and is noticed in the larger chromo- 

 somes which are nine times as long only by their distal chiasmata 

 becoming terminal {cf. Ch. XII). 



(h) The fragment is usually associated at one end only, in organisms 

 with complete terminahsation, although the major chromosomes are 



