i9i2] SHULL— LYCHNIS AND PAPAVER 121 



result is a "dominant white" if the inhibition of all pigmentation 

 is practically complete, or there may result parti-colored forms 

 exhibiting various color-patterns, or the dominance of what appears 

 to be a lower grade of pigmentation over a higher grade when the 

 inhibition is localized or otherwise incomplete. 



One of the earliest known and most familiar examples of domi- 

 nant white is found in the plumage of domestic fowl, in most breeds 

 of which white is epistatic to all colors, but not always quite per- 

 fectly so. It was soon found, however, that not all of the plumages 

 of white fowl are of the same nature, for the "Silkie" fowl's white 

 plumage is recessive to colors. Dominant and recessive whites 

 have been discovered in a number of other cases, both in plants and 

 in animals. Bateson (i, p. 105) and Gregory (7) found that 

 white-flowered primulas with red stems are dominant whites, 

 while those with green stems are recessive whites; 2 Keeble, 

 Pellew, and Jones (9), and Miss Saunders (10) have demon- 

 strated dominant and recessive whites in Digitalis purpurea; and 

 East (4, pp. 81 f .) has shown that an inhibitor for blue aleurone-color 

 exists in some maize plants though absent in others. 



In many cases, perhaps generally, the inhibition is not quite 

 complete, and dominant whites are often distinguishable by the 

 possession of patches or washings of color not found in recessive 

 whites. Similar incompleteness of action of inhibitors is seen in 

 the occasional appearance of rudimentary horns or "scurs" in 

 pure-bred polled cattle, in the development of a few feathers on 

 the legs of pure clean-legged fowls, the production of short awns 

 or "beards" on "smooth" wheat, oats, etc. 



Not only are there dominant and recessive whites, but there 

 are also different kinds of these, dependent upon the fact, now 

 well known, that the same visible effect may be attained in various 

 ways. It has been demonstrated that pigmentation is generally 

 due to the interaction of at least two independent factors. When 

 only two such factors are required, e.g., C and R, there may be 

 three kinds of recessive whites, one lacking C, one lacking R, and 



2 While this is the general rule, Keeble and Pellew (8) have found exceptions 

 in the variety "Pearl," which has dominant white flowers and green stems, and in 

 "Snow King," in which both dominant and recessive whites were found associated 

 with dark red stems. 



