RELATIONS OF ANIMAL MORPHOLOGY 247 



(as in the Plymouth Rock) and spangled (having centre of feather 

 of different color from periphery). 



Comb: Single, pea, rose (flat, covered with tubercles, like a file), 

 walnut; replaced by crest. 



Legs: Feathered, featherless; black, blue, yellow, horn-color. 



Body -shape: Short and chunky; tall and slender. 



Now the various varieties of fowl are made up of various com- 

 binations of these characters. Thus we may have Plymouth Rocks 

 which, instead of having bars, are pure white, or all buff; or the 

 single comb may be replaced by a rose comb (when they are called 

 Wyandottes); the usually clear legs may be feathered; and, finally, 

 they may be " bantamized." 



Any desired characteristic in the whole catalogue of poultry 

 characteristics might be engrafted upon an original Plymouth 

 Rock stock. We might put on it the crest of the Polish fowl or the 

 twisted feathers of the frizzle, or the loose barbs of the silky, or the 

 taillessness of the rumpless, or the long tail-feathers of the Japanese 

 long-tailed fowl. All this is, of course, possible because of the cross- 

 fertility of the races having these different characteristics. By 

 similar procedure we might make a white, blue-eyed, deaf, long- 

 haired, tailless, seven-toed cat; engraft the horns of the Dorset 

 sheep upon the hornless Southdown; add the fecundity of the two- 

 nippled horned Dorset to the multi-nippled condition of Dr. Alexan- 

 der Graham Bell's flock. 1 We might expect, after some experience, 

 to do this with the same certjainty that we can get calcium chloride 

 and carbonic acid out of a mixture of hydrochloric acid and marble. 



The bearing of this illustration, I repeat, is to show us that char- 

 acteristics of species are entities, not a little of whose interest lies 

 in the question of their origin in each case. When we know how 

 such characteristics arise, then we may call them forth at will, and 

 so determine the evolution of organic form. For the present it is 

 sufficient that by the acquisition of new characteristics new species 

 have arisen from preceding ones. 



This assertion is justified by the examination of any extensive 

 synopsis of species. Take, for example, De Bormans's synopsis of 

 Forficulidse in Das Tierreich. 2 Take any synoptic key at random. 

 Apterygida japonica has two large tubercles at the end of the abdo- 

 men. Apterygida allipes has four small ones. Anisolabis xenia differs 

 from A. Uttorea by slightly smaller size, and especially by having 

 two teeth in the forceps in the male, or three in the female, instead 

 of none at all. I do not mean to assert that species have arisen only 



1 Bell has given an account of his flock in Science, ix, 637, May 5, 1899, and 

 Science, xix, 767-768, May 13, 1904. He has also published privately (1904) a 

 catalogue of his sheep. 



2 De Bprmans, A., and H. Krauss, 1900, -Das Tierreich, 11 Lief. Forficulidce and 

 Hemimeridce, Berlin, xvi + 142 pp. 



