QUEEN-REARING IN ENGLAND. 57 



The Mendelian scheme of inheritance has been found 

 to hold good for a great diversity of characters in plants and 

 animals such as the absence or presence of horns in cattle, 

 the pea comb and the single comb in fowls, the absence or 

 presence of the waltzing habit in mice, and susceptibility or 

 resistance to rust-disease in wheat, to mention only a few. 



So far, we have considered the case of only one pair of 

 differentiating characters in an individual, but the same re- 

 sults occur in the case of any number of pairs of characters. 

 In the case of two pairs of differentiating characters we get, 

 in the first generation of the hybrids, individuals all showing 

 the two dominant characters. In the second generation we 

 get nine individuals showing both dominants, three showing 

 one dominant and one recessive, three showing the other 

 dominant and the other recessive, and one showing both 

 recessives. But it is not so easy to trace the results when 

 there are .several interacting factors modifying the same 

 part or structure, or when the factors concerned fail to cor- 

 respond with the characters that appear in the zygote, such 

 as factors for inhibiting or developing colour. 



Further complications are met with as the result of the 

 repulsion and coupling of certain factors, including some- 

 times the factors for sex, the inheritance of which in some 

 cases it appears to be possible to express in Mendelian terms. 

 It is often hard to trace the inheritance of utility characters 

 because they frequently are the result of many factors with 

 differences so fine that they can hardly be recognised. 



The study of Mendelism in the bee is hampered by 

 several special difficulties. First, we cannot control mating 

 in the ordinary way. Then there is the parthenogenetic 

 production of the drone, which is likely to have a disturbing 

 effect. Thirdly, the honey-bee is a highly specialised ani- 

 mal, and varies very little. There is some variation in size, 

 the eastern races being smaller than those of the west, but 

 apart from this the colour of the upper or dorsal side of the 

 abdomen is the only visible character that varies strikingly. 

 The variation consists in the extent to which the two colours, 

 yellow and black, displace one another. 



Turning our attention, firstly, to the workers, we find 

 that in A-pis indica, and in the artificial varieties known as 

 golden bees, the yellow extends over the three basal 



