136 POULTRY PRODUCTION 



the lack of a vital union between the sperm and .the ovum, 

 is usually caused by sterility, or aversion on the part of the 

 sire, barrenness on the part of the dam, or by physiologic 

 selection. It is not to be assumed that because a particular 

 hen gives few or no fertile eggs she is worthless as a 

 breeder. It often happens that males have favorites in a 

 flock with which they mate frequently while there are others 

 that are never served. It happens less often that two indi- 

 viduals, which produce healthy chicks when mated with 

 other individuals, produce no fertility when mated together. 

 Such a condition is referred to as one of physiologic selection. 

 The remedy in each case is the making of a new mating or, 

 where feasible, alternating males in the pen from day to day. 

 If upon mating with another male a female still returns 

 no fertility she may be assumed to be barren and useless. 



In the case of partial or total sterility on the part of a male 

 the low fertility of the eggs from all the hens mated with 

 him will necessitate his being discarded in self-defense. 



It would seem from the evidence at hand that infertility 

 in females of itself is not to be feared from the stand-point of 

 inheritance. It is rather an individual idiosyncrasy, highly 

 disappointing in present, but not serious in regard to future 

 effects upon offspring. In records furnished by Pearl and 

 Surface' it is shown that "There is no evidence that the 

 character 'fertility' of eggs (measured by per cent, of eggs 

 infertile) is in any degree or manner inherited." Very much 

 more serious from the standpoint of progeny is the frequent 

 occurrence of "dead in the shell," by which is meant that 

 while the egg is fertile it fails to hatch. Pearl and Surface^ 

 found that " The character hatching quality of eggs (measured 

 by the per cent, of fertile eggs hatched) is definitely inherited 

 in the female line and probably also in the male line." 



Selection for this point depends upon trap-nesting. The 

 time involved in visiting the nests several times a day and 

 recording the number of the hen laying each individual egg 

 is out of proportion to the price received for the products 

 and would fail to find a place in most schemes of manage- 



' Maine Bulletin No. 168. ' Ibid. 



