444 THE AMERICAN NATURALIST [VOL. XLII 



are rather wide discrepancies due to the fact that the 

 categories were not as carefully distinguished at first as 

 they should have been. Thus in the case of the cross of 

 Prolific Black Wax (black) with Ne Plus Ultra (dark 

 orange or " brown") many of the dark brown beans were 

 recorded at first simply as " brown," and the ratio found, 

 174 black: 47 seal-brown : 26 " brown," shows clear evi- 

 dence of the extent of error thus produced. A deficiency 

 of black is also apparent and is no doubt due to the re- 

 cording of some weathered blacks, as dark brown. In 

 the cross between Prolific Black Wax and Long Yellow 

 Six Weeks, 'the deficiency in the blacks and corresponding 

 excess in the dark brown is even more striking, giving the 

 ratio, 155 black: 55 dark brown: 9 yellow: 5 unclassified, 

 theory requiring 168 black: 42 dark brown: 14 yellow. 

 This factor D is also found to be present in the White 

 Flageolet, where, like the black factor, B, it is latent by 

 separation. 



The occurrence of dark brown as an invisible character 

 in the black bean may be called a case of latency due to 

 hypostasis, following the terminology suggested by 

 Bateson. 9 The unexpected character is not inactive, but 

 its characteristic manifestation is invisible because it is 

 hidden or inhibited by some other quality, and can only 

 become visible when the overlying or inhibiting quality is 

 removed by some means. 



This type of latency is no doubt very common, as it is 

 involved in many cases of simple dominance, as that 

 term is generally understood. If the " presence and ab- 

 sence" hypothesis has general validity (and there is a 

 very great preponderance of evidence in favor of it), the 

 term "dominance" should be limited to the relation of 

 the presence of any characteristic to the absence of that 

 same characteristic, and should not be used for the rela- 

 tion between two different positive allelomorphs by virtue 

 of which one hides the presence of the other. Bateson 



9 Bateson, W. Facts Limiting the Theory df Heredity. Science, N. S, 

 26, pp. 649-660, November 15, 1907. 



