306 



MARTIN BORRILL 



three genomes and chromosomes of the remaining genome of G. fluitans. Pairing would 

 thus be primarily allosyndetic between one genome from each parent, and occasionally 

 autosyndetic, between chromosomes of the plicata genomes. Occasional pairing would 

 also take place between chromosomes of these three genomes and slightly homologous 

 chromosomes of the fourth genome. 



It appears that G. fluitans and G. plicata have a common ancestor, which may be 

 G. declinata, since this species is closely related morphologically (Borrill, 1956). 



Acknowledgments 



My thanks are due to Professor T. G. Tutin who suggested this problem, to Professor 

 E. T. Jones, Director of the Welsh Plant Breeding Station, and Mr. A. R. Beddows, 

 Head of the Grass Breeding Section, for facilities for writing up the results : and to 

 Dr. J. R. S. Fincham and Mr. Keith Jones for advice and discussion of the cytological 

 problems involved. 



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