102 



MEIOSIS IN DIPLOIDS AND POLYPLOIDS 



and their structural relationship has been proved by the experiments 

 of Kuwada and his collaborators (i934' ^935 \ ^/ D., 1935, and 

 Ch. XII). 



During diakinesis the nucleoli become detached from their 



Fig. 31. — The history of relational coiling of the chromosomes with 

 intermittent pairing. The coiling of unpaired segments 

 persists at diplotene since they cannot form chiasmata. a, 

 centromere ; b, end of paired region ; c, intercalary unpaired 

 region ; d, intermittently paired region ; e, f, distal unpaired 

 regions {cf. Fig. 29B) ; g and h, chiasmata ; k, chiasma g, ter- 

 minalised. (D. ,1935 c.) 



organisers on the chromosomes and, as a rule, gradually disappear. 

 In some plants, however, they come to lie like a cap on the surface 



