MUTATION, FERTILITY, AND LONGEVITY IN INBRED JAPANESE TURTLE-DOVES. 45 



birds was found at autopsy to have but a single kidney; such phenomena of develop- 

 ment are inconceivable on any other ground than that the "germinal bases" of 

 these characters were modified. These several germinal modifications Avere all 

 associated in i^recisely the two most strikingly "mutant" young. 



(2) The entire family of about 17 young (including embryos) show a signifi- 

 cantly restricted term of life, demonstrating that gametes of reduced potency were 

 being generally produced; furthermore, at least 4 eggs tested absolutely infertile. 



(3) The mutational features here, like most mutations hitherto observed, 

 involve the loss of characters. 



(4) That the white mutational mark was not an adventitious somatic mark 

 of temporary value was proved by the fact that the parent "mutant" lived for 

 2^ years and that it suffered no apparent change, certainly no reduction of white, 

 in its several plumages, while the "mutant" offspring of this bird replaced, when 

 adult, their "mutational" first plumages with similar or identical or intensified 

 "mutant" plumages. Furthermore, the last two "normal" birds of the season 

 classified as "normal" in their first plumage showed advances toward the "mutant" 

 condition in feathers developed later. This fact is described in detail in the 

 section treating of the autopsies of this family. The mutational characters in 

 question were, therefore, rather accentuated than diminished in the individual 

 ontogenesis. 



(5) Finally, though breeding tests were limited in this case to the data already 

 given, such breeding tests have been quite thoroughly made in the case of at least 

 two seemingly quite analogous cases: (a) The " Zenaida mutation," noted in 

 Chapter X and full,v described and illustrated in Volume I. This later mutation 

 has to do with the appearance of a white triangular mark in the feather-tips of 

 the general plumage. Here, too, the original "mutant" arose in September- — again 

 the period of weakest germs. And (6) a second case, the "guinea-pigeon muta- 

 tion," in which a loss of red, a lightening of the general color in the direction of 

 the rock-pigeon, occurred, and which was likewise shown to be inherited in a frac- 

 tion of the offspring. This latter "mutation" is also fully illustrated and described 

 in Volume I (Chapter IX) of these works. 



Autopsies of T. Orientalis No. lOS and No. 433 and of Their Younc:, Hatched in 1912. 



An answer to many questions which will arise in connection with the highly 

 interesting family just described can be supplied only by the following information 

 secured at the time of death of the various members of the family. The detailed 

 statement concerning the "mutational" exhibitions of the several individuals 

 concerned is also best given here. 



Autopsy, 108 d'.— Found dead March 8, 1913. On the previous day this bird did not seem sick, 

 and at no previous time was it thought to be sick. Weight on February 18, 1913, showed, however, 

 that the bird was considerably too light (218 jiiaiiis). Was always a very quiet bird. Two small 

 testes, two normal kidneys,^ and other viscera aii|)arciitl\- iiDrnial, tliough feces somewhat greenish; 

 a little food in crop. An evident collection of white mucus-like material at internal nostrils, but 

 no canker found; brain apparently normal. Indeed, the examination failed to show why this bird 



' The last of the young (801) of the 1912 series was found December 13, 1912, to have but a single kidney. The 

 parents and the other offspring which died later than did No. 801 were examined to see whether, by any chance, 

 another instance of this unusual abnormality might be found in the same family. 



