144 RAYMOND PEARL 



animals and the controls belong to two different strains or 

 blood-lines. 



Because of the writer's belief in the fundamental importance 

 of the general problem with which this paper has to do it seems 

 desirable to take the space necessary to give complete data as 

 to the breeding of all the foundation animals used in this study, 

 covering a period of four years before the beginning of the ex- 

 periments. These data are given in the form of pedigrees. A 

 pedigree extending through four ancestral generations is given 

 for each one of the ma tings listed in the first column of table 2, 

 or in other words, for all the stock used in the experiments, since, 

 of course, the pedigrees of all the full brothers and sisters in one 

 family will be identical. In these pedigrees I have used the 

 same conventions to indicate ancestral repetition (inbreeding) 

 that have been employed in my earlier papers on inbreeding 

 (Peai-1, 19 and later papers in the same series). A solid black 

 circle against an animal's number indicated a primary reappear- 

 ance, a cross within a circle denotes a reappearance resulting 

 from the fact that some later individual in the ancestral series 

 has been primarily repeated. 



We may first consider the pedigrees of the families furnishing 

 the pure Barred Plymouth Rock females to the alcohol experi- 

 ments. These pedigrees are arranged in ascending order of 

 mating numbers. 



The numbers in the body of the pedigree are bird numbers. 

 The males are designated in nearly all instances by a number 

 alone; the females by a number and a letter. When a bird's 

 number is followed by the letters 'O. F. S.' it is to be under- 

 stood that this bird formed a part of the original foundation stock 

 with which the writer's poultry breeding experiments started. 

 Information regarding the sources of this original foundation 

 stock will be found in Pearl 17 (ip. 137 and 138). 



