THE BREEDING OF CHICKENS 1 08 



and the progeny, which always represent a first cross, are 

 never used for breeding purposes. Tluis it is said tliat for 

 producing Pliiladelpliia capons a cross nuicli employed is 

 that of the Light Brahma and White Plymouth Rock. 

 The offspring always carry half their blood from each breed. 

 For producing market ducks a cross much used is that of the 

 Pekin and Aylesbury. In such breeding it should always 

 be considered which is the better of the two reciprocal 

 crosses. 



Such a practice as this is sometimes erroneously referred 

 to as line l^reeding, because both lines of stock are bred pure 

 and only the first cross used. 



PURPOSE OF SELECTION. 



The purpose of selection is to jjrevent the birth of indi- 

 viduals not suited for production. In pursuance of this 

 purpose the points to be selected for in the order of their 

 importance are (1) constitutional vigor and capacity, {2) 

 hatching power, (3) egg production, (4) longevity, (5) early 

 nuiturity, and (G) breed and varietal characteristics. 



With the producer, from the nature of the case, selection 

 is confined to the first and the last three points. In most 

 cases it will be confined to the first and the last. For the 

 second and third he must depend upon the breeder. If 

 grading is carried on, selection so far as the producer's own 

 flock is concerned is further limited to females. 



Constitutional Vigor and Capacity.— Tlie appearance and 

 n;anifestation of maxuniun \igor and \italit\' can only be 

 present when all organs of the bod\' that ]ia\'e to do with 

 digestion, circulation, resi)iration, and the nervous system 

 which controls all, continuously perform tlieir full work. 

 Tliis maxhnum efficiency of all organs makes up constitution. 



That constitutional vigor is the foundation of good i)r<j- 

 duetion cannot be o\"erem])Iiasi/,cd. The best inheritance 

 ct)nceivable, with regard to all otiier points of selection, is 

 useless unless there is physical stamina as a foundation. 

 Without it, inheritance is as heljjless as a dynamo that has 

 no conducting cable to coimect it with its motors. It is the 



