FACTS OF INHERITANCE 155 



occur in man. Human eyes may be arranged in 

 two groups : (a) those with brown pigment on the 

 outer as well as on the inner surface of the iris 

 (usually browns and greens) ; and (b) those without 

 such brown pigment on the outer side, but with 

 some pigment on the inner side (blues and greys). 

 It appears, from the researches of Hurst and of 

 Prof, and Mrs. Davenport, that the first type is 

 dominant and the second recessive. Hurst also 

 gives some evidence that " fiery red " hair behaves 

 as a recessive to brown, and that the musical sense 

 is recessive to the non-musical. The clearest case, 

 as yet, is that peculiar condition of the hands and 

 feet known as brachydactyly, which Farabee and 

 Drinkwater have foimd to be dominant to the 

 normal condition. Of great interest also is Mr, 

 Nettleship's account of the descendants of one 

 Jean Nougaret (born 1637) who was afflicted with 

 night bhndness — a condition apparently due to loss 

 of the visual purple. There are records of over 

 2,000 individuals; and the night blindness is 

 dominant over the normal. During two and a half 

 centuries no normal member of the family who 

 has married another normal, whether related or 

 not, has ever transmitted the disease. 



Practical Importance of Mendelism. — The 

 work of the Mendelian school of experimenters 

 since 1900 is full of achievement and promise, and 

 no naturalist can help envying those who have been 

 able to share in it, aU the more that their dis- 

 coveries are full of practical as well as theoretical 

 import. Prof. Bateson writes : " If we want to 

 raise mangels that will not run to seed, or to breed 

 a cow that will give more milk in less time, or milk 

 with more butter and less water, we can turn to 



