44 



BATESON AND PUNNETT 



ack?iowledge on page 59 that '^ive have jwt perceived any circum- 

 stance to which the distinctio?i can be attribute d^ I have noticed 

 that my students are often satisfied with a name and do not always 

 require an explajiation as well. 



The clue to under sta?iding this paper lies in the data presented in 

 the table on page 58. These data show that both pairs of genes are 

 completely independent i7i themselves., aiid show results to be antici- 

 pated under the laws of chance. When the results are combined^ 

 however., the data deviate so greatly from that expected in the 

 independent assortment of units that it is necessary to conclude that 

 the iiidependence has been lost. Bateson and Punnett do not satisfac- 

 torily explain this loss, although inf ormatio?i in the literature would 

 have enabled them to do so. Suttojfs 1902 paper (page 21) suggested 

 that there must be more than a single gene on each chro?noso?ne as 

 a C07isequence of the greater ?iumber of characteristics tha?i chro- 

 mosomes. Sutton, however, could not prove this conjecture. Bateson 

 and Fumiett have the data which do so, but did not recognize this 

 fact. The need to keep up with the current literature is a paramount 

 one in biology . The data demonstrate most satisfactorily the exist- 

 efice of non-independe?it loci, which we now call ^''linked,''' and 

 the existence of crossing over between the loci through the excha?7ge 

 of chromosome parts, for their data show that the loci can be sepa- 

 rated. 



POULTRY 



The following table shows the 

 results obtained respecting comb char- 

 acters and extra toes. The numbers 

 prefixed to the experiments enable the 

 reader to trace the relationships in the 

 case of all cross-bred birds. To save 

 space the relationships of the pure- 

 bred birds are not given. No case was 

 seen in which this was found to influ- 

 ence the result. Slight and equivocal 

 indications of a change of "prepo- 

 tency" due to in-breeding were men- 

 tioned in Report 1. Fuller experience 

 strongly suggests that these appear- 

 ances were due to accidental fluctua- 

 tions. 



T u u^ T^r> • IT DR DD 



In the tables, DR is Fi,— r-, — r— , are, 



respectively, heterozygous and homo- 

 zygous dominants in Fo. 



— is extracted recessive in F2. 



The asterisk (*) means that the bird 

 had some special origin, which can be 

 ascertained from the breeding. R*, for 

 instance, may mean R from DR X R, 

 or R appearing in Fi (see Report 1, 

 p. 116), etc. These distinctions must 

 be indicated, but they do not seem to 

 affect the results. 



p.p., r.r., mean that the bird was 

 proved to be pure pea or pure rose; 

 i.r., i.p. and p.s., that it was proved to 

 contain single. 



Doub. means the longitudinally split 

 sijigle, described later. 



r.p. is the rose-pea, or "walnut" 

 comb, whether natural (Malay) or 

 artificial. 



The same bird is given as DD in its 

 matings with a single, and as r.r. or 

 p.p., in its matings with one of the 

 dominants. 



