54 ■ S. J. HOLMES AND H. M. LOOMIS. 



within the limits of probability. If the inheritance is partially 

 blended we should expect that with increased pigmentation of 

 either of the parents there would be an increased number of darkly 

 pigmented children ; and this we find. Inspection of Table I. 

 will show many other cases which may be quite as readily inter- 

 preted as cases of blended inheritance as of mendehzing. 



The principle of the non-transgressibility of the upper limit 

 which is laid down by the Davenports represents only a very 

 general tendency rather than a general law. Aside from the ex- 

 ceptions described Pearson records a family in which the two 

 parents had light gray eyes, four children had eyes like their 

 parents, while five others had black or brown eyes. De Candolle 

 found that out of 257 individuals born of parents both of whom 

 had gray or blue eyes 23 or 8.9 per cent, had brown eyes. I 

 have met with one instance in which both eyes and hair were of 

 a distinctly darker brown than they were in the darker parent. 

 As we are not dealing with hard and fast unit characters but with 

 different degrees of pigmentation it is not surprising that the eyes 

 of children should occasionally be darker than those of the 

 parents. This may account for some of the cases of apparent 

 blends, but, in the light of our results on hair color, it is hardly 

 probable that it can account for all. 



Hair Color. 

 Hair color, like eye color, is the result of more than one factor. 

 There is a granular dark brown melanin pigment which causes 

 variations in intensity from light brown or yellow to black ac- 

 cording to quantity. There is also a diffuse reddish pigment 

 which may cause variations from reddish yellow to dark golden. 

 These two kinds of pigment are usually mixed in various propor- 

 tions ; auburn and chestnut brown for instance arise from a com- 

 bination of the two. Both these kinds of pigmentation appear to 

 vary continuously and independently. The reddish pigment is 

 frequently obscured by the brown. It may appear in children 

 of parents, with dark brown or black hair, but does not occur in 

 children of Hght-haired parents who have no red pigment. Our 

 data on the inheritance of red are meager, but so far as they go 

 they confirm the conclusions of the Davenports on the inherit- 

 ance of this color. 



