Il8 AGRICULTURAL RESEARCH AND THE FARMER : 



SO that the highest grade of laying hen, producing eggs some 

 of which will hatch into cockerels and others into pullets, trans- 

 mits the high-egg-laying capacity only to her sons, and not to 

 her daughters. The high-grade layers must therefore get this 

 factor from their father , and this explains why such high prices 

 are paid to-day for the cockerels from hens with a high egg- 

 record. In the case of the Hamburgh-Sebright cross, it was 

 found that the silver cock transmits the " silver " factor both 

 to his sons and his daughters ; the silver hen, on the other hand, 

 transmits " silver " to her sons, " gold " to her daughters. When 

 a silver hen is mated with a gold cock, all her sons are silver and 

 all her daughters gold. The experiments have further shown 

 that chicks which will feather into silvers can be distinguished 

 in the down from those which will become golds. If, therefore, 

 silver hens are mated with gold cocks, the sexes of the chicks can 

 be told with certainty on hatching. The breeder who uses this 

 type of mating is in a position to kill off all his unwanted cockerels 

 at hatching, and to rear double the number of pullets with the 

 same plant. Thus it is possible, by a careful choice of breeds, 

 to avoid one of the most serious difficulties met with by poultry- 

 breeders who rear large numbers of pullets for egg-production ; for 

 with many of the best egg-laying breeds it is not possible to 

 distinguish the sexes with certainty until they are several weeks 

 old, and the rearing of young birds is an expensive process. 

 The sex-linked colour inheritance exhibited by the Hamburgh- 

 Sebright cross is not limited to those breeds, but also appHes 

 to certain others. For instance, in the Leghorns, the sexes can 

 be separated on hatching if Duckwings and Browns, or Cuckoos 

 and Blacks, are used for the cross ; in the Wyandottes, by using 

 Silvers and Golds ; in Plymouth Rocks, by using black and barred 

 birds. There seems to be no good reason why these types should 

 not be improved up to the best egg-laying standard, and if that 

 were done, the question of sex-determination on hatching would 

 no longer be a difficulty. 



The third series of experiments in poultry is connected with 

 the peculiarity of hen-feathering in the Sebright cock. This 

 investigation has not yet been concluded. It has already been 

 demonstrated that the factor for hen-feathering in the germ 

 cells acts as a dominant to normal feathering, but intermediate 

 types frequently occur, and the nature of these is now being 

 studied. The case is of general interest in that it is an example 

 of a normally female character becoming associated with the 

 male, in which sex it may give rise to effects not found in the 

 female. The association of a secondary sexual character with 

 the sex in which it is not normally found is not uncommon in 

 animals, and the present case in poultry is a clear cut and 



