90 MAINE AGRICUIvTURAL EXPERIMENT STATION, IQIO. 



recently described by Hagedoorn,* the inheritance o£ shank 

 color and the case of the silky fowl as described by Bateson,** 

 etc. Bateson (loc. cit.) devotes a chapter in his recent book 

 on heredity to a discussion of these known cases of sex-limited 

 inheritance. 



In the remainder of this paper the hybrid pullets will, for the 

 sake of convenience, be designated as either "barred hybrids" 

 or "black hybrids." 



THE HATCHING, MORTALITY AND SEX OE THE HYBRIDS. 



The hatching records for the matings which produced the 

 hybrids are given in Tables 4 and 5. These data are of 

 interest chiefly from the standpoint of the physiology of repro- 

 duction. It is well known that in many cases in plants it is 

 possible to make a cross in one direction, while the reciprocal 

 cross entirely fails to produce offspring. In other cases the 

 fertility is greatly reduced in the cross in one direction as com- 

 pared with the reciprocal. Is there any relation of this kind 

 in the crosses of poultry with which this paper deals? The data 

 in the following tables are of interest in this connection. It 

 should be said that all of the mated females, whether Barred 

 Rocks or Cornish, were pullets. The male birds were cockerels. 

 All were under the same conditions during the mating season, 

 and had the same food and treatment. The eggs were all incu- 

 bated in the same type of incubators, under uniform conditions. 

 For the sake of comparison a table (Table 6) giving the hatch- 

 ing records of pure Cornish Indian matings is included. In all 

 of these tables "Percent hatched" means percent of fertile eggs 

 hatched. 



In the cross Cornish Indian Game J' x Barred Plymouth 

 Rock 5' the data for which are given in Table 4, two differ- 

 ent males were used with the same females in the course of 

 the breeding season. The matings with the two different cock- 

 erels are separated in the table, and each group is summed and 

 averaged by itself. 



*Hagedoorn, A. L. Mendelian Inheritance of Sex. Roux's Archiv. 

 Bd. 28, pp. 1-34, 1909. 



**Bateson, W., Mendel's Principles of Heredity. Cambridge (Univ. 

 Press). 1909. 



