122 MEIOSIS IN DIPLOIDS AND POLYPLOIDS 



chromosomes are terminalised to the same end a multiple chiasma 

 is formed (see Figs. 40, 44 and 47). This consists in the terminal 

 association of the two chromatids of each of the chromosomes with 



Fig. 39.— Chromosomes of complete nuclei of diploid and triploid 

 Ttdipa at diakinesis. The numbers of chiasmata are given under 

 each configuration. Top, twelve bivalents in diploid T. Ges- 

 neriana. Middle, nine trivalents, three bivalents and above, 

 three corresponding univalents in a triploid variety {cf. Plate IV) . 

 Bottom, twelve trivalents in the same variety, and a chromatid 

 diagram of these. (Note the triple chiasma in the fourth from 

 the left.) X 2000 (from D. and Mather, 1932). 



chromatids of two different chromosomes. Triple and quadruple 

 chiasmata have been described in Tradescantia, Aucuha, Primula, 

 (Enothera (Catcheside, 1931), Rosa (Erlanson, 1931), Avena (Katter- 

 mann, 1931), Campanula (Gairdner and D., 1931), and Hemerocallis 



