MUTATION, FERTILITY, AND LONGEVITY IN INBRED JAPANESE TURTLE-DOVES. 47 



Rectrices and coverts white or whitened when present, except for two middle rectrices which were 

 normal (ends broken off). These perfect rectrices had no obvious constrictions at bases; practically 

 all others did. These latter mostly short and obviously stunted. Not a single full-grown primary 

 in either wing, and but one full-grown secondary (normal color it was) in the two wings. Most of 

 the stunted secondaries and their coverts were gray or whitened at one or all parts, and 2 tertials 

 were found to be obviously turned to gray in their unfolded portions not far above the terminal 

 constrictions. 



Autopsy, SSGd'. — Died March 26, 1913. Two kidneys; left foot with toes curled and useless; 

 testes small, not emaciated, but bird small ; yellowish over peritoneum and pericardium; also diseased 

 (yellowish) streak within wall of gizzard. Primaries, secondaries, and rectrices all, or nearly all, 

 stubby, broken, contracted roots — many of these whitened. 



Autopsy, 801. — Died December 13, 1912. Sex doubtful; undeveloped gonads, two in number. 

 Only one kidney, ivith the normal site of the other perfectly clean, whitish bone, free of tissue! Feathers 

 much stunted; color white to very gray. Always a weak bird; two "club" feet. 



INBREEDING. FERTILITY, AND LONGEVITY IN THE OFFSPRING OF JAPANESE TURTLE-DOVES OF 

 PAIRS 4 AND 5. 



In view of the results of the breeding of "mutant" 108, as just given, it 

 will now be well to present data upon the breeding and inbreeding of his 

 brothers and sisters; also these data for his half brothers and sisters, and further 

 the facts learned from crossing many of these individuals with other species — 

 St. risoria and St. alba. 



Brother-and-sister matings. — Five pairs of the earlier young of cf T. orienialis (2) 

 X 9 T". orienialis (2) were mated inter se. The results show that the germs of related 

 doves do not attain the strength of the germs which produced the parents them- 

 selves. In only a single instance did any of the numerous eggs of these matings 

 produce a young that lived as long as its shorter-lived parent. These matings — 

 22 X 21, 22 X 14, 25 x 23, 40 x 60, 35 x 30— are treated fully in the accompanying 

 tables, and briefly in the following paragraphs. The origin of all the birds concerned 

 may be seen in table 19. 



In the first of these matings of brother and sister, both parents being under 

 maturity, the average life of (3) offspring is (for 22 x 21) 2^ months. For 14 x 21, 

 when both parents were 1 year older, this average (for 4) is 9 months. The total 

 production of eggs for pair 22 x 21 (table 21) during more than a year is only 8; 

 and 50 per cent of these were unhatchable. The same female when a year older 

 and with an older mate produced at least 8 eggs in less than a year and all of those 

 tested (4) were hatched. The early death of the male of the 22 x 21 mating is a 

 further pertinent fact in a consideration of the weakness of those germs. 



When the birds of the next mating (25 x 23) were but little more than a year 

 old they were able to hatch 2 young; at 2 years 4 of 6 eggs hatched, but the j^oung 

 were short-lived. In their third year the only 2 eggs known to have been laid 

 were hatched ; the young again were probably short-lived (table 22). The immature 

 brothers and sisters, in mating 40x60 and 35 x 30 (table 22), gave progeny (3) 

 with an average length of life of 3 months, with one striking exception (from 35 x 

 30), which lived about 60 months. It is notable that the male parent of this 

 exception lived longer than any other bird of the group of parents now being con- 

 sidered (and at 10 years is still alive and partially fertile with an overworked 

 St. alba). In 7 of the 8 pairs of eggs for which the data are adequate, the first egg 

 of the clutch produced a stronger or longer-lived bird than did the second egg. 



