274 



Inheritance in the Groundsel 



Some of the discrepancies may be due to the difficulty of recognising 

 the various types. RRkh plants cannot however be mistaken, yet there 

 was only one and not 12 as expected. Although five plants are marked 

 rrHH, not one of these was a typical non-radiate lanugitiosus — the 

 production of which was one of the chief objects of the experiment. 

 The single RRhh plant was a perfect example of a radiate praecox. 



Treatirng // as dominant over h, the table becomes 



RR Rr rr 



Found 

 Expected .. 



Treating H and R as dominant over h and r, we get (compare 

 Table XI) : 



Found 



Expected ... 



The process gets rid of all discrepancies of importance, but at the 

 same time obscures the very important facts revealed by the fuller 

 analysis — the great dearth oi RRhh and rrHH plants. This is a point 

 of interest to which students of genetics might pay greater attention. 

 Now that the heterozygotic forms are being more acutely studied, it is 

 probable that many similar results will be brought to light and help 

 to increase materially our knowledge of the actual mechanism of 

 segregation. 



a 



Fig. 28. 7?Ex3 Fig. 29. J?rx3 Fig. 80. J?rx3 Fig. 31. rrx3 



Enlarged drawings of individual flowers by Miss M. Brockington. Fig. 28 — a ray floret of 

 erectus, radiatus, RR ; Figs. 29 and 30 — ray florets of the hybrids praecox x erectus, 

 radiatus and lanuginosus x erectus respectively, Rr; Fig. 31 — a disc floret of erectus, rr. 

 Note the presence of the five corolla lobes in Fig. 30. 



