206 . THE AMERICAN NATURALIST [Vol. XLII1 



4. Conversely red-haired children result from the 

 union of two "red hair" gametes. If there is no black 

 pigment to be considered all children, in such cases, will 

 have red hair. If one parent has visible red and the other 

 none (though probably heterozygous) then about half of 

 the children show the lipochrome pigment and the other 

 half the melanic pigment (Table X, b). If neither parent 

 of red-haired children shows red in its (dark) hair then 

 expectation is that only three sixteenths of the offspring 

 will have red hair. Table X, c, shows only those families 

 in which red actually occurs. Now in some families with 

 the potentiality of red in one quarter of the offspring, 

 but having only four or fewer children, a red-haired child 

 may fail to occur and such a family would be excluded 

 from the table. Such an exclusion would tend to reduce 

 the proportion of non-red offspring in the total. Conse- 

 quently instead of 86 per cent, of the offspring in Table 

 X, c, being non-red, actually only 61 per cent, are such. 

 In the families given there are numerous cases where 

 the red haired are to the non-red haired offspring as 3 

 is to 13 or as nearly so as the size of the family permits. 

 This is true of the Bal, Elt, Fro, Gri, Ram, Sco and Tay 

 families. The other families show not unreasonable 

 divergencies from the typical 3 to 13. 



5. All results are in accord with the statement that red 

 and black constitute two independent series ; that red is 

 dominant over no red, as the deeper shades of melanic 

 pigment are dominant over the lighter ; and that the dense 

 granular melanic pigment tends to hide the diffuse pig- 

 ment. Thus in Table VIII the gametes of the red-haired 

 parent may be given as n.R; those of the brown-haired 

 parent as N.r; where N, n. are abundance and sparsity 

 of melanic pigment, respectively, and R, r presence and 

 absence of lipochrome (red) pigment, respectively. Then 

 the zygotes will be of the various forms: nR (red soma), 

 NR (brown or black, red hypostatic), Nr (plain brown 

 or black), n.r. (flaxen to light brown). The matings of 

 Table IX, a, are of the order (NR, Nr, nR, nr) X (NR, 



