304 



MARTIN BORRILL 



Chiasma Frequencies 



Chiasma frequencies were determined in plants from several populations, the mean 

 per bivalent being 1.33 for G. declinata 1-34 for G. fluitans and 1-13 for G. plicata; hence 

 G. plicata has a lower chiasma frequency than the other species. The detailed results 

 are given in Table 5. , . 



Table 5. 



Chiasma frequency in species of section Glyceria 



Herb. No. of 



No. Cells 1 xta 



G. declinata 



IB 10 6-3 



413 9 6-6 

 427 12 6-3 



436 9 7-4 

 446 10 6-7 

 448 8 7-7 

 458 10 7-4 

 464 12 7-8 

 468 10 6-8 

 506 10 6-6 



Total 100 — 



Average — 6*96 



G. fluitans 



408 10 11-7 



409 10 13-9 



422 10 14-0 

 431 10 11-9 

 435 10 13-2 



437 10 14-4 

 439 10 10-9 

 452 10 12-6 

 454 10 15-0 

 460 10 14-9 

 475 10 13-0 

 490 10 14-7 

 498 10 12-1 



Race K 10 13-8 



Total 140 — 



Average — 13-2 



G. plicata 



400 10 18-2 



414 10 19-1 

 418 10 15-9 



423 10 18-0 

 430 10 18-0 

 444 10 16-8 

 472 10 16-9 



Race G 10 13 5 



Total 80 — 



Average — 17-0 



Chiasma Frequency 

 Bivalents per cell with 



Mean per 



2 X ta 3 X ta Bivalent 



3-3 0-4 1-45 



3-0 0-4 1-37 



3-3 0-3 1-40 



2- 3 0-2 1-27 



3- 0 0-3 1-36 

 2-2 — 1-22 

 2-4 0-2 1-30 



2- 1 0-1 1-21 



3- 2 — 1-32 



3- 1 0-3 1-37 



2-86 0-21 1-33 



8-0 0-3 1-43 



6-0 0-1 1-35 



6- 0 — 1-31 



7- 9 0-2 1-41 

 6-9 — 1-41 



5- 5 — 1-28 



8- 7 0-4 1-47 



6- 7 0-1 1-34 

 5-0 — 1-27 

 5-0 0-2 1-26 



7- 0 — 1-30 



5- 2 0-1 1-32 

 7-6 0-3 1-41 



6- 2 — 1-31 



6-5 0-12 1-34 



1- 8 — 1-09 

 0-9 — 1-04 



4- 0 — 1-20 



2- 0 — 1-10 



2- 0 — 1-10 



3- 2 — 1-16 



3- 1 — M5 



4- 5 — 1-22 



2-7 — M3 



