104 



P. F. YEO 



Hirtellae, the members of which, as far as is known, are all diploids. However, the 

 question whether var. reayensis shows, in common with var. notata, any irregularities at 

 meiosis, has not been gone into. This was due to the fact that meiosis had finished in 

 a large proportion of the spikes fixed, and work on the material was stopped after a clear 

 count had been obtained, so that few divisions were seen. The count showed n=22; the 

 material was from Bettyhill, W. Sutherland (E304). 



(13) E. rivularis Pugsl. Plants dug up in turf in Cwm Idwal, Caernarvon, in June 

 1952 (E123), were grown in the greenhouse and produced seed. In 1953 the count of 

 n = ll was obtained from a plant grown from this seed. 



(14) E. anglica Pugsl. The number n = ll was observed in E71, plants dug up as 

 seedlings at Holmsley, S. Hants; E150, Box Hill, Surrey; E157, Mickleham Downs, 

 Surrey; and E168, Charnwood Forest, Leicester. 



(15) E. hirtella Jord. var. polyadena (Gren. & Roux) Pugsl. Material from Lawers, 

 Mid Perth (E253), had n = ll (Plate 10, fig. 5). 



(16) E. anglica X micrantha. A single individual (E185C) was found on a heath 

 near Withypool, Exmoor, S. Somerset, at a point where the parent species came into 

 contact. The plant resembled E. micrantha in habit, small foliage, and dark anthocyanin 

 pigmentation. The flower had no lilac in it, unlike those of the surrounding E. micrantha, 

 and was slightly larger than those, with a larger lower lip, in this respect diverging from E. 

 micrantha in the direction of E. anglica. The foliage had scattered rather long glandular and 

 eglandular hairs. {E. anglica has dense long-stalked glands; E. micrantha is sub-glabrous). 

 On the main axis it had flowered at five successive nodes, but there had been no develop- 

 ment of any of the capsules. The percentage of normally formed pollen grains was 

 investigated by staining with cotton blue in lactophenol. Of 998 grains from one flower 

 31, or 3-1 per cent, were normal in appearance. 



The shoot apex from the main axis, and one from a branch of this plant, were fixed, 

 and preparations of pollen mother ceil meiosis obtained from both. The chromosomes 

 tended to be clumped, a condition met with occasionally in other material, and this 

 made interpretation difficult. It was clear that a number of univalents, up to eleven, 

 was present, and also some bivalents. What appeared to be larger bodies are evidently 

 groupings of two or three bivalents. Interpreting the chromosomes on this assumption 

 it was possible to count most of the bivalents and univalents in four cells, there being a 

 residue of one or two doubtful bodies. These could be interpreted as large univalents 

 and, if this was done, the conclusion was reached that there were eleven bivalents and 

 eleven univalents present. One of these cells is shown in Plate 10, fig. 6. Figures 

 1 and 2 show interpretative diagrams of two of them. These interpretations were made 

 from the preparations themselves, but they are not certainly correct. In each of the 

 cells illustrated there is, in fact, one body that looks like a multivalent. These are indicated 

 in the diagrams; that in fig. 2 is very suggestive of a trivalent. The interpretations 

 given, however, are the only ones that give a total of 33 chromosomes. Since the basic 

 number is 11, and since the number in this hybrid is certainly in the neighbourhood 

 of 33, an interpretation that gives exactly this number is more likely to be correct than 

 one giving a different number. 



The anaphases seen were too obscure to give any information, but at telophase 

 univalents were occasionally present, faintly stained, at the equator. These lagging 

 univalents usually numbered only one or two. 



General Observations on the Cytology 



The chromosomes are of moderate size. The size varies within the complement but 

 in meiotic material it is difficult to describe the differences in detail, as von Witsch (1932) 



