FECUNDITY IN THE DOMESTIC FOWL 



PEDIGREE LINE 0650366 



9E239(24)XcT55J 



224 



354(75)Xd"55' 



Mean =26 



9 F309 (OD) 1 ' 



263(44) (9 G 



362 (43) 



216 (41) X <?5t9 I 



9F301 (7) 



223 (74) 



224 (42) 



9 F242 (27) 



221 (39) X #566 



9 F271 (37) 

 9 F171 (46) 

 Mean =jj. 4 



34 



42 



56 



164 



(40) 

 (5) 



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 reappeared from generation to generation 

 with practically no change. In two instances quite certainly, and possibly 

 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 occurred 

 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 fecundity. In 1908 there appeared in it one individual of distinctly 

 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 fecun- 

 dity genotypes (d ?l cf554 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 

 exception 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. 



Leaving this bird out of account because pathological, the mean winter 

 production of the family is 52.8 eggs, very strikingly different from the 

 average (9.67 eggs) of the birds of the same generation in the main low line 

 in which the mutation appeared. 



Two other daughters of the mutant E248 were mated to o" D31,a bird 

 known not only to belong to a genotype of mediocre to low fecundity, but to 



IO Bird died during winter period. 



