Wright: Color Inheritance in Mammals 



235 



venient to suppose that both enzymes 

 I and II are strong on the back and weak 

 on the belly. Similar cases are com- 

 mon. Another sort of example seems 

 to be present in the tiger pattern of cats. 

 In yellow cats the pattern is shown by 

 alternate orange and cream stripes 

 which on our interpretation must indi- 

 cate alternate stripes of high and low 

 potency of enzyme I. In tabby cats, 

 the intense stripes are solid black, the 

 pale stripes show yellow ticking which 

 seems to require that enzyme II also 

 be strong in the former, weak in the 

 latter. 



CONCLUSION 



In the present paper an attempt has 

 been made to relate the findings of 

 the biochemist in regard to melanin 

 pigment with the great mass of curious 

 relations between colors which have 

 come to light in genetic work. A 

 scheme is given which is designed to 

 show the inter-relations of the different 

 mammalian coat colors and a classifica- 

 tion of color factors is suggested. It is 

 hoped that these will be of use in or- 

 ganizing our present very extensive 



knowledge of color inheritance and in 

 aiding in the discovery of new facts, 

 or at least in leading to a better scheme 

 and classification. 



Finally the bringing under one point 

 of view of biochemical and genetic 

 facts would have great intrinsic in- 

 terest. The present paper attempts 

 merely to trace the character — coat 

 color — back one stage in development. 

 Instead of considering factors as acting 

 on this one character, they have been 

 divided into two sets acting on two 

 characters, production of the hypotheti- 

 cal enzymes I and II. Suggestions 

 have been made in certain cases in re- 

 gard to further tracing back of the 

 action of the factors. A more thorough 

 comparison than has yet been made of 

 the effects of factors in all combina- 

 tions should yield much data bearing on 

 the process of pigmentation and give a 

 very much more complete understand- 

 ing of the heredity of color than we have 

 at present. By constant comparison 

 of the deductions from such work with 

 the findings of the biochemist, it should 

 be possible in the end to establish a 

 very pretty correlation of results. 



Does Racial Intermarriage Lead to Sterility? 



That the intermarriage of different 

 races leads to diminished size of family 

 is the conclusion of Prof. Albert Ernest 

 Jenks of the University of Minnesota. 

 His studies in Minneapolis, Minn., 

 Sioux Falls, S. Dak., and in Lincoln 

 County, Minn., convince him that 

 "human hybridization is a powerful 

 factor in America, that it does affect 

 fecundity — being a process toward the 

 gradual niimerical weakening of the 



groups amalgamating. It is thus an 

 increasing factor in America, affecting 

 fecundity to the greatest extent in those 

 families most completely amalgamated." 

 He adds that "as yet the 'American' 

 is not a pure-bred ethnic group but is an 

 extremely amalgamated group, and, in 

 consequence of the amalgamation, is a 

 decidedly impotent group." His in- 

 vestigations are summarized in the 

 Holmes Anniversary Volimie. 



A Valuable Variety of Barley 



The introduction of the single im- 

 proved variety of barley called "Plum- 

 age" has added at least $1,250,000 a 

 year to the value of the English barley 

 crop, according to the estimate of the 

 British Board of Agriculture. Wheats 

 produced by the Institute of Plant 



Breeding at Cambridge have also made 

 a notable contribution to the national 

 wealth. Little has been done in Eng- 

 land, the board complains, to improve 

 the varieties of roots, rotation grasses 

 and clovers, or any of the minor field 

 crops. 



