84 Experiments with Primula sinensis 



If we assume for the moment that the observed divergences from the simple Mendelian 

 ratios are due to differences of this kind, then, if di, 02, 63 represent respectively the 

 fertilities of the gametic unions Short x Long, Long x Long, and Short x Short, the results 

 described above would give 



$1 :02 : 03=100: 89 : 44. 



These figures are quantitatively in general agreement with the relative fertilities, as 

 determined by the average number of seeds per capsule, of the various kinds of union 

 between plants of different form, the corresponding figures being 132 or 100 : 84 : 44 

 (see p. 83, footnote). The comparison must not be pressed too far, since the actual 

 fertilities of the various unions, observed in any set of experiments, would depend in part 

 upon racial characters. The agreement is however rather suggestive and, taken in con- 

 junction with the results of our examination of the observed numbers by other methods, is 

 suflScient to justify further investigation. 



The point can be tested experimentally by determining the constitution of all the 

 short-styled plants in a number of large F2 families; we should then find whether there is 

 any significant divergence from the theoretical proportion of 1 pure : 2 heterozygous 

 short-styled offspring. 



Abnormal Cases. 



A case was described in the previous report^ in which the entire 

 series of crosses made with a certain short-styled plant (No. 6/3) showed 

 a definite and consistent departure from the normal expectation. The 

 evidence already given showed that No. 6/3 behaved as an ordinary 

 heterozygous short-styled plant when used as the female parent in 

 crosses with long-styled plants, while its male gametes almost exclu- 

 sively bore the dominant character^ The case promised to be of some 

 interest, but unfortunately all the plants used as parents for succeeding 

 generations proved to be normal pure short-styled plants, giving short- 

 styled offspring only, when selfed and crossed either way with long- 

 styled plants. No further elucidation of the case is therefore possible. 

 The F^'s from crosses of this race with long-styled plants showed normal 

 distribution of shorts and longs in the offspring, and are included in the 

 F^ table given on p. 80. The results of all the crosses in which this 

 particular race was used are recorded in the tables given on pp. 85, 86. 



1 Bateson and Gregory, loc. cit. p. 584. 



2 By an unfortunate error the statement made in the first paragraph on p. 585 of the 

 previous report is inverted. The context makes it clear that the statement should have 

 read: "the ovules of No. 6 gave a mixture of longs and shorts, and consequently were 

 of two kinds, while all the plants raised from it as male were shorts." 



