INHERITANCE OF EGG CHARACTERS 



13 



D. Time to Standard Egg Weight 

 The time required from first pullet egg to a standard egg weight of 56.7 

 grams 24 ounces to the dozen was recorded throughout the experiment. Table 

 2 summarizes the results with reference to the percentages of birds in the three 

 lines that actually attained this standard egg weight during their first laying 

 year, and the mean time required. Complete data are not available on the 

 first three generati; 



!. — Percentage or Dat/ghters Reaching Standard Egg Wz 

 and Mean Time Required 



Lines A and B behaved in a similar way throughout the experiment with 

 respect to the percentages of birds attaining standard eg; In these 



:-- : lines there was a consistent increase in percentages of qualifying birds 

 from year to year. Line C was inconsistent in the last generation. I" ■ 

 probable that gene A was carried by a considerable number of individuals in 

 line C in the last generation. 



Mean days required to reach standard egg weight did not behave in the same 

 way in the three lines. Line A showed an increase in mean time to standard 

 egg weight as the experiment progressed: Line B showed a decrease in average 

 time required: while line C showed a significant increase in the last three 

 generations. The fact becomes evident from these data, in comparison with 

 data on egg weight during the hatching season, that egg weight in the normal 

 hatching season does parallel the time required to reach standard egg weight. 

 In other words, individuals that are slow in attaining a 24-ounce egg weight 

 are more likely to produce smaller eggs for hatching. 



?-- :.-.-. r.. rre made for the qualifying birds in the three 



lines on the basis of time to standard egg weight. No line gave a normal 

 variability curve. Line A showed the closest approach to a normal curve, but 

 was definitely not normal. This fact shows that time to standard egg weight 

 is not a simple fluctuating character, but is governed by a series of chara 

 If the time to standard egg _ rre governed by two or three heritable 



genes, bimodal or trimodal frequency graphs would appear. There was no 

 evidence of such a simple situation in these data. The mean time to standard 

 egg weight for all daughters qualifying in the three lines during the experiment 

 was as follows: line A 69.9 days. '.:ne B 42J ,. and line C 52.3 days. Since 

 these data do not represent a normal frequency distribution, the pre: 

 error of the mean could not be calculated. 



