BIOSYSTEMATIC STUDY OF SOME GLYGERIA SPEGIES - II 



301 



Methods 



The method adopted for fixing and staining was based on the procedure developed 

 by Thomas (1940), using acetocarmine for small chromosome fruit material. In 1952 

 Carnoys' fluid (Darlington & La Cour 1947) was used alone; in 1953 the material was 

 premordanted by the addition of a few drops of ferric chloride to the fixative, which gave 

 improved staining of G. declinata and G. plicata. 



Tubes of fixed material were stored without deterioration, in a deep freeze reirigerator at 

 — 15 °C until required for use (Davies 1952). The preparations were made permanent 

 by infiltration using triacetin, an oily liquid of low volatility completely miscible with 

 acetic acid. 



The preparations were irrigated at 30°C on a hot plate by means of a drop of triacetin 

 placed at the edge of the cover glass ; this was drawn through the preparation by the 

 evaporation of the acetic acid and carmine, giving clear mounts in 24 hours; the cover 

 glasses were then ringed with Canada balsam.. To minimise any evaporation due to 

 imperfect ringing the slides were stored at 5°C, and showed little or no deterioration after 

 eighteen months. 



Meiosis was found to occur when the inflorescences were young, soft and entirely 

 enclosed within the leaf-sheaths. One floret per spikelet in a few of the spikelets in each 

 panicle showed the stages diakinesis, metaphase, anaphase. When a floret contained 

 anthers at first metaphase, the one above showed prophase and the one below, second 

 division. Stages before diakinesis were not sufficiently stained for study. In G. declinata 

 the number of pollen mother cells was small, about ten per loculus. 



Chromosome Numbers 



The chromosome numbers reported in this and previous studies are shown in Table 2 

 All the counts made subsequent to 1939 verify the basic number x = 10 given by Maude. 

 The basic number x = 7 given by Stahlin (1929), which apparently is erroneous, has been 

 discussed fully by Fitzpatrick (1946). No intraspecific chromosomal races have been 

 found and since in this study meiosis has been examined in many plants it is possible 

 that such races do not occur, supporting the view put forward in a previous paper 

 (Borrill, 1956). 



Table 2. 



Chromosome numbers of Sectioi} Glycerin 



Species 



Stdhlin 

 (1929) 



Maude 

 (1939-40) 

 Britain 



Church 

 (1942) 

 N. Amer. 



Fitzpatrick - 

 (1946) 

 Britain 



Church 

 (1949) 

 N. Amer. 



Knaben 

 (1950) 

 Norway 







^ § c 2 



Present 

 Study 

 Britain 



G. 



declinata 





20 



20* 



20 



20 



20 





20 



20 



20 



G. 



plicata 



28 



40 





40 













40 



G. 



fluitans 



28 



40 



40 



40 



40 





40 







40 



G. 



X pedicellata 









40 













40 



* This plant was originally identiried as a form of G. fluitans and named G. coohii by Swallen (1941 



Meiosis (See Plate 21) 

 G. declinata and G. fluitans 



In these species pairing occurred as bivalents only, ten pairs in G. declinata and twenty 



