738 Michael F. Guyer 
ural selection, it may be by sexual selection, perhaps, directly 
or indirectly, by other factors of the environment; nevertheless, 
the pattern tends to reveal itself in some stage of the progression, 
‘or progressions, which are characteristic of the group as a 
whole.” 
The writer does not care to enter into a general discussion of the 
vexed question as to which is phylogenetically the older pattern, 
the stripe or the bar. It seems plausible to suppose, as some do, 
that all groups of birds have not followed the same order in the 
development of their respective patterns and that what is archaic 
in one group is not necessarily so in some other. While the first 
plumage in the young of Gallinz is striped, as pointed out by 
Darwin, still we must bear in mind that this striped appearance 
is due to the relative arrangement of deeply pigmented and of 
colorless feathers respectively which are themselves unstriped. 
The underlying physiological conditions which produce such a 
pattern, therefore, must be very different from those which pro- 
duce an individually striped or barred feather, since one has as its 
basis an arrangement of the feathers on the bird, the other, a series 
of processes in a particular feather. 
On such feathers as are wholly or partially concealed one would 
naturally look for the phylogenetically older color pattern, if one 
admits of the theory of selection in any degree, since these hidden 
parts would not be subject to the disturbing influences of natural 
or of sexual selection, which so far as color patterns are concerned, 
require the parts affected to be visible. It is precisely in such 
places that one still finds most of the traces of barring in the domes- 
tic guinea (Figs. 17, 23, 27, Plate IV) and inthe pheasant (Fig. 14, 
Plate III). Furthermore, in such hidden regions is found the 
principal portion of the color pattern of the domestic guinea which 
persists and even shows evidences of augmentation in regressive 
'Tnasmuch as the question of evolution in definite directions irrespective of utility does not fall pri- 
marily within the scope of this paper, the reader is referred for discussions of the subject to the original 
papers of such investigators as Hyatt, Escherich, Haacke, Cope, Eimer and Whitman. See especially: 
Eimer, Th.: On Orthogenesis, Open Court Pub. Co., 1898. Whitman, C. O.: In the Proceedings 
of the Congress of Arts and Science, Universal Exposition, St. Louis, 1904, vol. v. Also, Bul. Wis- 
consin Acad. of Sciences, Jan., 1907. 
