BATESON AND PUNNETT 



DISCUSSION OF RESULTS 



Comb-characters 



DR birds, r. or p., produced in vari- 

 ous ways, bred with R birds (s.c.) of 

 various origins gave 449 D to 469 R. 

 DR X DR gave a total of 211 D to 

 83 R. These totals ^ are not very far 

 from the 1 D : 1 R or 3 D : 1 R sever- 

 ally expected. Individually, however, 

 there are some wide departures from 

 these expectations, and it is practically 

 certain that in several cases there was 

 distinct numerical inequality of D and 

 R gametes, as seen in the case of Peas 

 and elsewhere. On the other hand 

 there is no indication that DR individ- 

 uals themselves are capable of sub- 

 division into classes, and all the figures 

 available point to a monomorphic dis- 

 tribution of the aberrant individuals 

 round the mean case of equality in 

 output of D and R. There is also dis- 

 tinct evidence that the proportional 

 output of D and R may change at 

 different times in the life of the same 

 individual. There is, as yet, no clear 

 case, unfortunately, in which a DR $ 

 giving an aberrant number with one 

 s.c. 9 was simultaneously bred with 

 another s.c. 9 . It is practically certain, 

 nevertheless, that the irregularity did 

 not, in any way, depend on the reces- 

 sives, for the same bird often gave 

 regular numbers with 1 DR and aber- 

 rant numbers with another. In these 

 comments it is assumed that no gametic 

 selection occurs. 



"Extraction" had no influence on 

 the proportions, as may be seen from 

 the table. 



An example of a 

 $ extracted pure 

 dominant (rose) 

 occurs in Experiment 103 and 157 



47 



Very few F2 p.c. birds have been 

 tested, and, as it happens, no case of 

 pure extracted dominant F2 has been 

 piet with, but 9 644 from DR X D 

 was, however, a pure DD (Experiment 

 110). 



Purity of Recessive (Single) Comb. 

 —Singles of various origins, derived in 

 several ways from rose and from pea 

 crosses, when mated together, have 

 never given either rose or pea. In all, 

 such matings have given 800 singles. 

 In one case (Experiment 105) four 

 specimens of a new form of comb 

 appeared, together with 131 singles 

 (included in total just given). 



This mating was made of 4 Fi reces- 

 sive 9 's from a "non-Mendelian" or 

 mixed Fi from rose-comb, bred with a 

 similar Fi recessive $ from pea-comb. 

 In the four mutational birds the combs 

 were imperfectly split posteriorly (see 

 p. 113). These must be regarded as 

 illustrations of that twinning or du- 

 plicity which has been observed in so 

 many median organs. A similar case of 

 posterior duplicity in a rose-comb - 

 came in Experiment 166. Such double 

 "single" combs are not very rare in 

 fowls, but are not found in any recog- 

 nized breed, the Houdan "leaf" comb 

 beinff, in some ways, distinct. 



Relation of Rose to Pea Co?nb.—\n 

 1902 this inquiry was begun by cross- 

 ing DR rose-combs with DR pea- 

 combs (Experiment 124), These birds 

 mav' respectively be called r.s. and p.s. 

 They gave, as was expected, four 



1 They include chicks kindly bred by 

 Mr. Assheton (not given in the table) from 

 birds raised in Experiment 33, as follows: 

 DR X R, 16 r. 6 s. DR X DR, 36 r., 16 s. 



- In 1904 a case of partial duplicity in a 

 pea-comb has occurred. A split s.c. like the 

 mutational form occurred also in Experiment 

 176a. 



