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TIIK AMERICAN NATURALIST [Vol. LV 



smoky white. Fortunately for the problem in hand the 

 localization of this pigment in the down of certain regions 

 of the body is quite characteristic and quickly recognized. 

 While a blue-splashed chick is frequently very light blue, 

 as noted by Bateson and Punnett (1906, p." 20), the pig- 

 ment is not localized on the top and back of the head, the 

 wings in the region of the bow, and on the thighs, as it 

 is on the potentially white chick, and the impression con- 

 veyed is very different. In potentially white chicks the 

 romiges, which may be seen just starting to grow out 

 from their follicles, are pinkish white and exhibit not the 

 slightest trace of pigment. In the same feathers of the 

 blue-splashed chick, on the other hand, there is a very 

 noticeable bluish cast and usually at least one remex that 

 is distinctly pigmented. 



Though in pure-bred white Plymouth Eock and white 

 Wyandotte chicks the pigment granules in the down are 

 typically rod-shaped this fact is not of assistance in 

 classifying with respect to white and blue-splashed off- 

 spring from crosses involving the factor R, since under 

 its iiiHuciicc 1 lack pigment granules are round whether 

 in a i)(it('utiall\ wliite or a blue-splashed chick. 



Xot all fhicks from pure-bred white Plymouth Rock 

 and white Wyandotte matings exhibit this juvenile pig- 

 ment. Some can only be recorded as white. It is of 

 interest that the only chicks, three in number, which were 

 originally described as ''white, no pigment" or ''creamy 

 white" and later used in a breeding pen, have all proved 

 to carry a factor for dominant white, as described in a 

 later section of this paper. The number of such birds 

 which have been tested is small and no general conclu- 

 sions can be drawn, but the results are suggestive. It is 

 rather interesting to note that a photograph of a group of 

 white Plymouth Rock chicks in "The Plymouth Rock 

 Standard and I^rced Book" (American Poultry Associa- 

 tion, 1919, p. 419), which is the official guide for the breed- 

 ing and judging of all Plymouth Rocks, shows individuals 



