MUTATION, FERTILITY, AND LONGEVITY IN INUKKD .lAI'AM I ; I.', 



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

 ment are inconceivable on any other ground than thai tin- .^rinina] IM 

 these characters were modified. These several germinal mollifications \\.-n- nil 

 associated in precisely the two most, strikingly "mutant " young. 



(2) The entire family of about 17 young (including embryos) show a >ini!i- 

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

 being generally produced; furthermore, at le:ist 4 eggs tested absolutely infertile. 



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

 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 uhite, 

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

 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 lea-t 

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

 Chapter X and fully 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 Sept/ //// / 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 OP T. ORIENTALIS No. 108 AND No. 433 AND OF THEIR YOI-NC, lluvm:i> 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, 108c?, Found dead March 8, 1913. On the previous day this bird did not semi >u-k. 

 and at no previous time was it thought to be sick. Weight on February IS. 1!H 

 that the bird was considerably too light (218 grams). Was always a very quirt 

 testes,two normal kidneys/ and other viscera apparently normal, though i 

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

 no canker found; brain apparently normal. Indeed, the examination fail. 



3 The last of the young (801) of the 1912 series was fmiml December 13, 191 2. to have l.ut : , smci- kidney The 

 parents and the other offspring which died later than did No. 801 wen examined to see v 

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



