THE MUTATION THEORY AND MUTATIONS. 173 



the following: (1) The mutation behaves 40 more as a "dominant" than as a "reces- 

 sive" character; (2) the character often appears in a reduced or fractionated form, 41 

 the white triangular spot of the wings assuming the form of a white crescentic tip; 42 

 (3) only two of the first-generation hybrids (Z-ZN 1 and 6) seem to have been bred 

 (most of this progeny died early); one of these (Z-ZN 1) was mutational (pi. 85, 

 figs. D, E) and the other "normal or nearly " ; it seems probable that all of the mutants 

 that have appeared (in other than the first generation) are derived 43 from Z-ZN 1 

 the first mutant young (from a first egg in life) of the original mutant; (4) the inheri- 

 tance of the mutation, in neither the first nor later generations, is limited by sex. 



TABLE 7. 



cf Zcnaidura carolinensis (11) May 27, 1906. 



9 Zenaicla vinacco-rufa MUTANT (21), hatched Sept. 28, 1906; August 21, 1908; 24 months. 

 9 Al. July 15, HX)7. Z-ZN1 "mutant" on breast, lower neck, sides of head; Oct. 11, 1911; 52 months. 



All. July 17, 1007. Z-ZN2 normal; Dec. 5, 1907; 4H months. 



Bl. Mar. 21, 1908. failed to hatch (exposure). 



B2. Mar. 23, 1908. failed to hatch (exposure). 

 9 Cl. Mar. 28. Z ZN3 "mutant"; strong, except at bend of wings and back; May 17, 1908; 1 month. 



C2. May 30. Z-ZN4 relieved, died before feathering; % month. 



cf Dl. Apr. 10. Z-ZN5 "mutant"; strong on head, breast and wings; Jan. 25, 1910; 2\^ months. 

 9 D2. Apr. 12. Z-ZN5 normal or nearly; Mar. 19, 1910; 23 months. 

 d" El. Apr. 24. Z-ZN7 normal, like D2; Oct. 1, 1910; 29 months. 



E2. Apr. 26. Z-ZN8 normal, like D2; June 9, 1908; IK months. 



Fl. May 14. developed near to hatching, but parents deserted. 



F2. May 16. developed near to hatching, but parents deserted. 



Gl. June 19. "development not completed"/"! now notice (July 9, 1908) that the dam (21) is not quite well. 



G2. June 21. "development not eomplcted"\ legs weak;' 4 this continued till death, Sept. 21, 1908." 

 9 HI. July 11. Z-ZN9 normal; Jan. 20, 1908; 6 months. 



H2. July 13. fully developed embryo, thrown from nest and broken. 



11. July 31. "failed to develop." 



12. Aug. 2. "failed to develop." (K, CCOO) 



One or two of the above topics arc touched upon in the author's description of the 

 first mutant offspring (Z-ZN 1); this statement is therefore given herewith in full: 



"This hybrid (Z-ZN 1) hatched July 30, 1907. 45 The mother of this hybrid is a 

 pure-bred Zenaida vinaceo-rufa and the father a pure-bred Zenaidura. 



'The mother has her Juvenal feathers marked by a conspicuous white triangular 

 or wedge-shaped spot, dividing the tip of the feather, as do similar marks in the 

 guinea-pigeon; hence I called her a 'mutant,' as she was quite strikingly different 

 from her mate or any other young zenaida I had raised. She had these spots on 

 the head, neck and breast, and wing-coverts and scapulars; but this, her hybrid 

 offspring, has smaller white spots, and only on the front neck and breast and on the 

 sides of the head (none on the wings) ; in short, it inherits the Juvenal mark of 

 its mother but in a degree that stands midway between the two parents the 

 mourning-dove sire having had no such mark. 



"This hybrid has of course the apical edge marks on the wing-coverts, and these 

 are quite whitish, but they do not dip in at the middle to form a dividing-mark. 



40 Sec note to table 7. 



41 See Vol. II, Chapter XVII. This character was thrown into a cross generally considered of generic value, and 

 the author has insisted (Vol. II) that when the wider crosses are made there is less of segregation, and clearer "frac- 

 tionation," of the characters involved. 



42 The editor finds that the feathers of other regions than the wing may sometimes show only an enlarged, crescentic 

 white tip; such birds are clearly intermediates of the normal and the strong or usual "mutant" offspring. To distin- 

 guish them I have called them "crescentics"; but on either side of these the lines are not sharp. 



41 As stutcd elsewhere, some of the Zenaida records were only very temporarily in the hands of the editor and were 

 never later available to him. In the absence of the complete record we can not be more definite on the above point. 



44 "The weakening probably began some time before noticed. This female (21) beg;in strongly transmitting 

 her juvenile pattern, but as she weakened the male gained control and produced the normal type." 



44 Photographed, kindness of Professor Keighard, Septemter 7, 1907. 



