42 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



and wing coverts are particularly affected with white; and (4) that the uniformly 

 dark feathers, such as primaries, secondaries, and rectrices, are more or less 

 uniformly grayed or whitened. 



In pi. 6 the extent of the variation of the second "mutant" (No. 98) is shown 

 along with the two parents. It will be seen that this bird is more strongly whitened 

 than was the preceding, but somewhat less so than the succeeding and final "mu- 

 tant." This second variant, like the first, was short-lived, and no further history 

 or illustrations of it are available. 



The last and most interesting of these "mutants" (No. 108) is shown at two 

 years of age in pi. 7. It will be observed that this final "mutant" was perhaps 

 the most striking variant of the series, and that the variant state had maintained 

 its exhibition throughout various molting periods. The nearly white tail and the 

 absolute displacement by white of the tj'pical dark centers of the individual 

 feathers are well shown. This bird was perhaps less wild, and notably more 

 quiet, than any individual of this species that the editor has observed. 



The Breeding of Mutant No. 108. 



Only No. 108 of these birds lived to maturity, and it only therefore was avail- 

 able for breeding tests. This bird proved to be a male, but refused to mate during 

 1911. In 1912 it mated with an immature relative (No. 

 433, hatched August 2, 1911). The relationship of these oios^-^^ee^-^^ 

 birds is completely given in the accompanying sketch ^* "* 



or diagram. The chief interest in breeding No. 108 !£ 



hes, of course, in determining whether the bird is a real ^^"^^ ^^ 



mutant, i.e., whether the marked somatic aberrations **" '^""""-^ill * ^2°. 



from the type pertain also to its germs. The illustra- "* '* ~<% 



tion already referred to shows how strikingly this bird 



differed from the parent species. We elsewhere (legend of pi. 7) record Dr. Whit- 

 man's interpretation of this marked "mutation" as the outcome of a "weakened 

 germ" — ^weakness associated with extreme age of the dam and inbreeding. 



The result of mating this "mutant" with the pure Japanese turtle (433) men- 

 tioned above is shown in table 20, and is of the greatest interest in connection with 

 the questions of the heritability of the variation, of the effect of season, overwork, 

 and inbreeding in "weakening" germs. 



It will be seen that from this pair 11 young were hatched, and lived long enough 

 to admit of their classification as normal or "mutant." Of these, 6 were normal 



Explanation of Plate 4. 



A. Expanded tail of normal Japanese turtle-dove, Turhir orientnlis, No. 94, of similar age with 



"mutant" No. 95. 



B. "Mutant" Japanese turtle-dove No. 95 and normal No. 94. Of similar ago; photographed 



together, Sept. 17, 1909, to show contrast. 

 No. 95 is much whitened in coverts, tail, neck-marks, and, in fact throughout the entire phunage. The dam of 

 this bird is now (Sept. 1909) al least 1.3 years old. She was imported in 1897, and at that time must have been one 

 or more years old. The old age of the dam and the mating with her son accounts for the very light color of the young. 



C. Profile view of "mutant" No. 95. 



This bird was the first to appear of three "mutants" of 7'. oricntaUs. It was the least striking color variant of 

 the three. It developed from an egg of Aug. 1.5, 1909. Photographed, Sept. 17, 1909. For pedigree see table 19. 



