ZENAIDURA AND ITS CROSSES WITH ZENAIDA AND HYBRIDS. 115 



and in still other groups of birds; (5) the zenaidas possessed the character in an 

 earlier stage of their phylogenetic history ;= (6) the "mutational" character per- 

 sisted, and still persists, through several generations in crosses with Zenaidura 

 carolinensis and its hybrids; (7) the character behaves in inheritance rather more 

 as a "dominant" than as a "recessive," but there is some reason to believe that 

 its behavior, as exhibited in the generic cross in which it has been perpetuated 

 can not be accurately described in terms of "dominance." 



The pedigree of the "mutant" (No. 21, see pi. 84, Vol. I) and of her mother 

 (12, pi. 83, Vol. I) are given in table 92. The following statement concerning the 

 "mutant" is taken from the record: 



This bird was hatched September 28, 1906. The front and sides of the head, neck and 

 breast, and abdomen, the wings and scapulars, and under tail-coverts, and even the tail- 

 feathers (below), are all marked with this mid-terminal, triangular "white spot," which 

 is the characteristic mark in the wing of the guinea-pigeon (pi. 81, Vol. I). 



This bird is just a little larger than is No. 20 (which is of normal color, hatched 

 August 18, 1906, from the same parents), but only a little younger. Both birds are now 

 (November 9, 1906) in juvenal plumage and can be compared and photographed side by 

 side. No one would take them for the same species, and yet they are from the same pure- 

 bred parents.^ I expect that these marks will disappear in the adult plumage.' If they 

 do, then we have what might be called a juvenal-stage mutation. In other words, a 

 character with all the appearance of a mutation, but transient. 



It is important to know if this character is entirely new, or if it is a great enlargement of 

 a minute feature of the normal juvenal feathers. The photograph of No. 20 shows just a 

 beginning of this character on the neck — just a mere line. This terminal dividing-mark is 

 not white in the normal form, but pale buff or pale brown. I have seen the same mark 

 nearly and of similar color in some young Japanese and European turtle-doves, in young 

 Leptoptila, and in the young of Florida ground-doves. 



This character (white triangular mark) is a pennanent character in the African guinea- 

 pigeon. In this species we should have no doubt about calling it a character. The muta- 

 tionist would hold that it is an immutable unit. Yet we see that it certainly is only an 

 enlargement of the very minute dividing-line. Even in this specimen it is reduced to mere 

 lines on the crown of the head and on the throat. What appears then to be a mutation 

 turns out to be not a really new thing, hxxi an extension and intensification of the normal mark. 



Is there any explanation for this? I can account for it only by referring it to the 

 hard time the bird passed durmg the first 2 or 3 days of its life. ... It may be 

 that the lack of food for the first two days was the cause of this enlarged mark — a sort 

 of albinism. >= (CC 0) 



It will be seen from table 93 that the "mutant" was bred when 1 and 2 years 

 of age to a male Zenaidura carolinensis. The "mutant" offspring in this cross 

 seem to arise chiefly from the stronger germs. 



' See Chap. IX, Vol. I. 



* The original records for the breeding of Z. vinacco-rufa are not available to the editor; the descriptions in con- 

 nection with the Zenaida "mutant" and of the several Zenaida hybrids form most of the materials at hand. — Editor. 



^ This prediction proved entirely true. — Editor. 



' In a note dated two j-eais later (in 1908) Whitman wrote: "This 'mutant' (21) hatched September 28, 1906, 

 from the second egg of the clutch," underlining the words "September" and "second." In view of the otlier data 

 then at hand on the relation which both season and the order of the eggs of clutch be;»r to the "strength of germs" 

 it seems certain that these points were at the latter date, to his mind, the most important considerations bearing 

 upon the appearance of this "mutation." At this later date he had also found, of course, that the mutational character 

 was inheriled, and was, therefore, not a phenomenon of merely transitory and somatic value. — Editor. 



