Caroline Pellew and Eva Richardson Sansome 45 



^^r ^^^ 



3 3 5f 3 3 



(a) 



H¥H 



4 2 2 4 



Fig. 6. Side view of first metaphase in semi-sterile plants. The association of four chro- 

 mosomes is orientated so that adjacent chromosomes are directed towards the same 

 pole. X 4000. 



