II38 



BREKDING 



Results of black and tan basset cross with fox terrier bitch. 



The question is next discussed : What will be the result of intermating 

 the above progeny. If, to avoid confusion, only one character at a time 

 is considered (monohybrid cross), the ist generation should, according to 

 Mendd's theory, beget black and tan individuals and spotted individuals, 

 and individuals with basset stature and with fox terrier stature respectively ; 

 all this in the ratio 3:1. In the case of the dihybrid cross, the conditions 

 are more complicated, because the different characters are formed into com- 

 binations. The writer draws up a table of gametic formulae, in which he 

 collects the 16 theoretical combinations of the determining characters. 

 According ot thfs table there would be formed in the 2nd generation in 

 addition to the 2 parent types, 2 biotypes : the spotted basset and the 

 black and tan fox terrier. The ratio of the 4 biotypes (differing externally) 

 would be such that among the 16 dogs there would be 9 black and tan 

 bassets, 3 spotted bassets, 3 black and tan fox terriers and i spotted fox 

 terrier : each biotype would correspond to a homozA^gous individual.' 



While demonstrating theoretically what was to be expected from the 2ud 

 filial generation, the writer reports the further course of these experiments : 

 the animals resulting from the ist filial generation were mated with each 

 other 5 times, and produced 32 individuals : 23 black and tan and 9 fox 

 colour. This result proves that the inheritance of the black and tan co- 

 lour of the basset and the spotted colour of the fox terrier follows the Men- 

 delian rule, and that the black and tan is alwa>-s dominant, while the spotted 

 character is recessive. Thus the ratio of the 5 matiiigs (23:9) agrees with 

 the ratio anticipated by theory (24 : 8). 



Of the 32 puppies 11 died, and the remaining 21 grew up well. Of 

 21 fully grown dogs there were 16 with basset body (one of them very short- 



