THE TURTLE-DOVE PATTERN IN 'I Hi: I'll, 1 ol I'KiKO 65 



field, disclose the direction of evolution, provide (tie investigator with ;t key to the 

 natural order of sequence in color-patterns, enable him to detect and to demon- 

 strate orthogenetic evolution, if such there be, and to discriminate nicely between 

 this and the results to be ascribed to natural selection and other intervening factor-. 



From such a vantage-ground one may proceed to work out detail- of evolutional 

 progress by the aid of comparative study of patterns at all stages and a ire- of 

 development. Juvenile phases of color-patterns become luminous as recapitula- 

 tions in the sense of the biogenctic law and do not stand as isolated prodigies of 

 natural selection or as meaningless exhibitions of mutation 



In the 500 or more perfectly distinct wild species (see table 1) with phyletic 

 relationships of easy determination in most cases; in the 200 or more domestic 

 races, all springing primarily from a single known wild stock 3 in all this abundance 

 of natural and cultivated forms, with a multitude of comparatively simple charac- 

 ters, the evolutional history of which can be largely deciphered in many cases 

 through comparative and experimental study, we find inexhaustible material for 

 just such test-cases as we desire. 



The more generally distributed patterns, such as occur only in the first plumage, 

 or only in this and the adult female plumage, furnish the chief problems. The 

 patterns of first interest are: (1) the light-edged feather; (2) the dark-c<l </nl feather; 

 (3) the dark-centered feather; (4) the transversely barred feather; marginal bar alone 

 dark and light, or light and dark repeated, V-shaped, vermieulate, wavy; (5) the 

 two-dotted feather; (6) the cross-barred wing; (7) the relation of black and iridesci 



The principles found to obtain in plumage patterns are: 



(1) The juvenal plumage presents the earlier type. 



(2) Females are less modified than males. 



(3) The upper surface is more modified than the lower surfari . 



(4) Repetitive marks (cross-bars) are multiplied from the ti/> inward t/rnrd the 

 base, the tip bars being the stronger and best defined. 



(5) The tendency is sometimes (usually) to lose murks and <jr<irHn(e In utti -color 

 or irhole-color; other times to strengthen and extend (?) the marks as <>ru<nnfnlnl 

 recognitional, warning marks. 



(6) The pale edge of the first feathers ix imribj direct In contitinon.t with the down, 

 and perhaps this relation accounts for its pale color (like the down). The tip 

 the barbs come nearest to the primitive color, because first formed. The pale edge 

 varies in width is wide in the turtle-doves, narrow in Colnmba liriu. and obsolescent 

 in young inca and others. 



(7) 77)e more primitive the ti/pc of color (lie ({nicker it /'.s reached: e.t/.. the Japan' 

 turtle-dove reaches it in the first plumage, while in other families the type of the 

 species is not reached until the adult plumage appears. Again, the inca-dove is 

 more primitive than the geopelias, and it is losing the light edge, which is so con- 

 spicuous in geopelias. 



'These remarkable phenomena, which, as a rule, in normal (level. ipnu-nt. furnish only fr.iKinentary ami iii-e.ni- 

 nected parts of past evolutional history, may l>e so extended liy suitable experiin. .vd elsewhere. KP.) as to 



demonstrate eomplete continuity of stanes in the passage to the adult pattern. 



' It is a cieat mistake to resort exclusively to domestic races, for here the ancestry contains so many unknown 

 elements that it is often impossible to refer phenomena to their proper sources. Kven the so-called "pure-!)!* 

 aie decidedly impure as compared with pure wild species. The ideal situation. - material, is to have pure 



wild species in abundance as the chief reliance and allied domestic races for subsidiary purposes. 



