No. 534] FECUNDITY IN THE DOMESTIC' FOWL 333 



Pedigree Like D65D366 



9E239(&#)Xc 



164 (5) 



224(^3) X<f 554 



9mW(SS)X<?D65< 



Zte{15)X<?551 



5 F242 



)X<?S66< 



9 G 65 ff«) 

 209 



.10-' (':</) 



544 (5) 



Jfean=20 Mean=38.. 



Mean=Z 



This line is shown graphically in Fig. 3. 



In the examples thus far given we have had to do with 

 pedigree lines in which a given degree of fecundity re- 

 appeared from generation to generation with practically 

 no change. In two instances quite certainly, and pos- 

 sibly in several others, a new and distinct variation has 

 suddenly appeared within a line and thereafter bred 

 true, thus presenting the characteristic phenomena of 

 mutation. The most striking instance of this sort oc- 

 curred in line D61D168 and may be given here in detail. 

 The main part of this line has already been discussed 

 (p. 331). It will be recalled that it is a line of low fecund- 

 ity. In 1908 there appeared in it one individual of dis- 

 tinctly higher fecundity than any other bird in the large 

 family of that year. This individual when bred produced 

 only high layers. In the next generation two of these 

 daughters were bred to males known to belong to high fe- 

 cundity genotypes (c?o*554 and 566). One of these matings 

 unfortunately produced no adult female offspring. The 

 other led to the production of six adult daughters, all of 

 which are relatively high layers, with the single excep- 

 tion of G495, which has a record of only one egg, and 

 that record is doubtful. This bird has probably never 

 laid an egg, and almost certainly is pathological. 



