,g4 The Illustrated Book of Poultry. 



head 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 

 grows. Dissection, however, demonstrates its true nature, an* proves that the head of the Poland 

 is altogether of unique conformation. The globular appearance is thus shown to be the result 

 of the elevated 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 future 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." 



Fi"-. 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.— Skull 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, amoqgst others on the canary, which do not usually possess it. A small amount of crest 

 does 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 



