396 
The Illustrated Book of Poultry. 
ik ad of the Poland chicken previous to the growth of the feathers of the top-knot. It has 
sometimes been supposed to consist of a thickened state of the skin, or of a fibrous structure 
beneath it, as also of a fatty substance, forming a nidus or cushion from which the future top-knot 
glows. Dissection, however, demonstrates its true nature, and proves that the head of the Poland 
is altogether of unique conformation. The globular appearance is thus shown to be the result 
of the elev ated form of the skull-cap itself, laying like a round marble on the top of the head. 
According to the extent and development of this globular prominence of the skull may the size of 
the futuie top-knot be accurately foretold ; hence, in the best specimens it is large, and seems 
to include the whole upper part of the head ; in inferior breeds with small top-knots it is but 
indistinctly developed. This test, says Dr. Horner, “ is so accurate, that whenever it is considered 
desirable to rear only the finest birds, all those which are found wanting in this respect may 
be safely discarded ; it is, in fact, the very shibboleth of Polands.” 
Fig. 87 is carefully drawn from the skull in the museum already alluded to, and shows the 
peculiarities plainly. Had their constant character been formerly known, and anatomists not been 
Fig. 87. — Skui.l of a Polish Fowl, showing Bony Cyst above the Orbits, 
and Chasm in the Bones supporting the Nostrils. 
led off the scent by the comparative uncertainty which we have seen to prevail, and which none but 
fanciers could be expected to dispel, we entertain very little doubt that in days when specific 
differences were less understood than they are now, the Polish would have been elected to the 
rank of a distinct species ; but at the present day there would be considered no ground for such 
a conclusion, as not only does the Polish fowl breed indiscriminately with other varieties, the 
progeny being perfectly fertile, but the peculiar formation of the skull, and with it the crest 
itself, with which it is vitally connected, can be “ bred out ” by crossing with the greatest facility. 
Such facts furnish a striking example of the essential difference between apparently trifling, yet 
real, specific distinctions, and other distinctive marks of seemingly far greater magnitude and 
moment, but which experience shows to be merely characteristic of varieties. So regarded, they 
furnish arguments of the strongest nature against the Darwinian theory of development, so far 
as that theory applies to the origin of real species ; though if attention be confined to the mere 
amount of external change effected, their tendency may appear the other way. No naturalist 
would consider mere crest as a specific distinction, since it has been developed in many families 
of birds, amongst others on the canary, which do not usually possess it. A small amount of crest 
docs not appear to involve necessarily any change in the skull ; but by selecting and breeding 
from birds with the largest crests, and thus developing that feature till it obtains the magnitude 
seen in the Polish fowl, we undesignedly influence the cranium also, till it assumes the character 
of the skull figured above. Striking peculiarities will be observed in two points. First, there is a 
