50 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



INBREEDING OF UNCLE TO NIECE AND ORIGIN OF AN INTERESTING FAMILY OF INBREDS. 



Besides the male "mutant" No. 108, whose mating with a relative has been 

 described at length, 3 of the offspring of his mother, T. orientalis 2, were inbred, 

 but in other than brother-and-sister matings, and founded stock not strong, although 

 strong enough to reproduce, and thus permit a further study of the effects on the 

 germs of continued inbreeding in these doves. In general the matings given here 

 are of uncle and niece. One such pair yielded a large family of inbreds which become 

 the center of interest in the next chapter. The data for this degree of inbreeding 

 is presented in three tables given herewith. These data strongly reinforce those 

 derived from the brother-and-sister matings, and from inbred birds out-crossed 

 to other species, in that they indicate that these immature and inbred doves may 

 produce offspring; hut not offspring that will live the normal span of life. The following 

 statement sufficiently analyzes the individual matings: 



The shortest and least instructive mating of the series concerns a male (40) 

 which, when not fully mature, tested at least partially fertile with a sister (table 22). 

 With a niece (88) this male was given two further tests of fertility (table 26a) 

 these two eggs hatched, but the young from the second egg of the clutch (laid last 

 of September) lived but 3 days. The other bird was a female that lived for 6 months 



The individual tabular records for male No. 76, during 3 years of matings 

 bring out the following facts: When the male was little more than 2 years old 

 and mated with a female of unknown ancestry though probably related and prob- 

 ably 3 or 4 years old, the progeny (3) averaged probably 9 to 10 months (table 26) 

 But when 3 years old, mated to an immature (2 years old) daughter of his sister (88) 

 only one of 7 young lived as long as 9 months. This one, however, from a strong 

 germ of the latter part of May, escaped at 25 months. 4 of the 7 young died at the 

 age of 5 to 9 months, and the last 2 of the season at only 1 month (table 26). During 

 the following year (1911), when the male was a little more than 4 years old and his 

 consort was reaching maturity (3 years), the progeny (about 25) lived 24+ months 

 (3 still alive). This particular family, whose detailed history is given in table 27, 

 it will be noted, is a large one and was produced under overwork; the term of life 

 of the ofTspring was, however, sufficiently long to permit breeding tests with many 

 of them. The results of the further special study of this family will be given in 

 the following chapter. 



The last pair of eggs for the seasons 1910 and 1911 produced birds with the 

 shortest life-term; and the longest life-terms are grouped toward the earlier part 

 of the season. Birds from the first egg of 3 clutches lived longer than birds from 

 the second; less long in 1 or (?) 2 cases. 



The sex data for the progeny of this male and his two consorts are in many 

 respects meager and incomplete ; combined with the data for longevity, they may 

 be compactly given as follows: 



1909, the (? related) nearly mature mate gave. , . . 2d'; 09 ; 1? (?9l months). 



1910, the inbred, miniature mate gave Icf ; -' 9 ; 5? (?S months). 



1911, the inbred, less immature mate gave 7c?; 9 9 ; 9? (24 + months). 



When, therefore, the parents were more mature, the progeny lived longer; 

 probably there was then, too, a higher proportion of males. 



A similar summary statement for the second of the two females (88) used in 

 the above matings is of interest. It will be noted that female No. 88, herself the 



