THE CYTOLOGY OF BRITISH SPECIES OF EUPHRASIA 



103 



(3) E. foulaensis Towns. A count was obtained from cultivated material (E227) 

 showing n=22. The seed came from live plants sent from N. Uist, Outer Hebrides, 

 in 1952, by Mr. R. G. West. 



(4) E. marshallii Pugsl. E311, Bettyhill, W. Sutherland, showed n=22. 



(5) E. curta Fries var. rupestris Pugsl. Cultivated material (ElOO) showed n=22. 

 ElOO was collected in Cwm Idwal, Caernarvon, in June 1952, and consisted of herbarium 

 specimens of E. camhrica Pugsl., and turves. The only plants that persisted in the turves 

 were E. curta var. rupestris, which was not generally in flower at the time the turf was 

 collected. Seeds were collected from the plants in the turves and grown in 1953. The 

 plants gave a small number of buds from which the count was obtained. ElOO therefore 

 consists of herbarium specimens of wild E. camhrica, and cultivated E. curta var. rupestris 

 from which the chromosome number was obtained. 



(6) E. occidentalis Wettst. n=22, from E192, Rame, E. Cornwall. 



(7) E. nemorosa (Pers.) H. Mart, emend. Lohr. Two counts were obtained, both 

 of n=22, one from E134, Bedford Purlieus, Northants., the other from E149, Banstead 

 Downs, Surrey. 



(8) E. confusa Pugsl. n=22, E175, from Withypool, S. Somerset. 



(9) E. pseudokerneri Pugsl. n=22; plants from the Devil's Dyke, near Brandon, 

 W. Norfolk (Plate 10, fig. 3) (E136), and Risby Poor's Heath, W. Suffolk (E143). 



(10) E. hrevipila Burnat & GremH. n=22, E245, Sparrowlee Halt, near Waterfall, 

 Stafford. In one cell observed, there is an indication that one pair of chromosomes is 

 represented by two univalents instead of a bivalent, but this is not certain. 



(11) E. hrevipila var. notata Pugsl. Two lots of material (E254 and E256) from 

 colonies about half a mile apart at Lawers, Mid Perth, were worked on. In both, n=22 

 was observed, but some buds showed 2n=44+l, the extra chromosome appearing as a 

 univalent, most frequently either at the edge of the metaphase plate, or well away from 

 it. The occurrence of an extra univalent can be accounted for by supposing that, in 

 one of the parents of an individual possessing it, there occurred a failure of disjunction at 

 meiosis, and that as a consequence of this both members of the pair went to one pole 

 at anaphase, giving pollen grains with twenty-three chromosomes, instead of twenty-two. 

 No anaphases showing evidence of this unsymmetrical distribution were seen, but pairing 

 failure in one pair of chromosomes at metaphase was rather frequent. Plate 10, fig. 4 

 shows a metaphase in E254 with twenty-one bivalents and three univalents. This has 

 the extra chromosome and shows the pairing failure that probably gives rise to it. It 

 will be noted that all three univalents are of approximately the same size, and that they 

 are about as large as the largest chromosomes among the bivalents. That these chromo- 

 somes were univalents was confirmed by Dr. J. R. S. Fincham, upon inspection of the 

 photographic negatives. The only suggestion that the two univalents are members of a 

 bivalent that have separated early is that they are in every case near one another. Dr. 

 Fincham pointed out, however, that as the univalents are almost always found at the 

 edge of the metaphase plate they are probably forced into this position by lack of a spindle 

 attachment, and thus have a good chance of appearing in the same part of the cell in the 

 preparation. The shape of these chromosomes indicates that they are true univalents. 



In fixing, more than one spike was usually taken from each plant, and all were fixed 

 together. Thus it is not known whether more than one plant in each gathering had 

 the extra chromosome, and, at least in the case of E256, not all the fixed material was worked 

 through. However, the extra univalent was found in both gatherings, and pairing failure 

 was observed in both, being seen several times in E254. 



(12) E. hrevipila var. reayensis Pugsl. This form, and E. hrevipila var. notata, are 

 the only European forms with long glandular hairs that are not classified in the Series 



