3IO R. M. STRONG. 



to be the white ring-doves of this paper. The results seem to 

 be similar to those which were obtained by me, so far as they 

 go. Two matings between "White Java" males and female 

 "Turtle doves" were made and ten offspring were obtained 

 four "dark males," four "dark, sex uncertain" and two white 

 females. 



Staples-Browne also crossed the blond ring-dove (called 

 "Barbary Dove" in his paper) with his "White Java" doves and 

 obtained results which are like those described by me in this 

 paper, except that in two matings between male blonds and 

 white females, three male and three female white birds appeared 

 in FI. The explanation of these results given by Staples- 

 Browne, that the male parents in these two cases were hybrids 

 is undoubtedly correct. He states that much difficulty was 

 experienced in obtaining pure "Barbary" stock. 



Records are thus at hand of the appearance in FI of white 

 birds, whenever a white male ring-dove is crossed with females 

 of at least two Linnaean species and also with the blond ring-dove. 

 The assumption that the females of all of these three species, 

 Turtur risorius, T. humilis and T. turtur are heterozygous for 

 color seems to me more difficult to accept than the idea that 

 the sperms of the male white ring-dove are responsible for the 

 FI white birds. 



According to the interpretation of these cases of sex-linked 

 inheritance which has been advanced by Spillman ('08), Bateson 

 ('09) and others, the following two assumptions may be made in 

 addition to those already stated (see Bateson, '09, p. 175): 

 "That when in FI the two dominant characters femaleness and 

 the 'somatic' factor co-exist, there is spurious allelomorphism 

 or repulsion between them, such that each gamete takes one or 

 other of these factors, not both." The following scheme though 

 familiar is repeated here for the sake of clearness in making a 

 comparison with the interpretation which I am about to propose. 



D = dominant. R = recessive. 



i . Dominant cf X Recessive 9 



composition DD cf cf RR 9 cf 



gametes all D cf R 9 



R rf 



