378 



The Journal of Heredity 



long been known which does not enter 

 into the hncar series just discussed. 

 These are the sooty yellows, sables, 

 and black-and-tans investigated by Miss 

 Durham,-"^ Little'" and Dunn.''- In the 

 sooty yellows more or less black pigment 

 is mixed with the yellow on the back, 

 while in black-and-tans the entire back 

 is black leaving only the belly yellow. 

 These variations are independent, ge- 

 netically, of the yellow factor and can be 

 introduced readily into grays, ]jroducing 

 gray-bellied blacks, and into blacks, 

 producing very dense blacks. The\' are 

 spoken of as deepeners of black. The 

 mode of inheritance is irregular and 

 has not been analyzed. Physiologically 

 these factors may be considered as 

 increasing the rate of production of 

 enzvme II, thus increasing the absolute 

 amount of the differentiation between 

 back and belly spoken of above and 

 giving the agouti factors more to inhibit 

 especially on the back. These deepen- 

 ing factors appear to have no effect 

 on the intensity of yellow as the belly 

 in black-and-tans may be any color 

 from red to white. They clearly belong 

 in class 2a3. 



VARIATIONS OF BLACK 



Two Mendelian factors are known 

 which vary the intensity of black with- 

 out influence on the yellow parts of the 

 coat, but which act in a fundamentally 

 different way from the deepeners of 



black just dealt with. The latter are 

 in a sense alternative in their affect on 

 pigment. With them a granule is 

 either black or yellow and the intergrade 

 between black and yellow in the fur is 

 sooty yellow. In the brown-eyed brown 

 mice,'^' and the pink-eyed lilacs,^* on 

 the other hand, the character of the 

 pigment seems to be really intermediate 

 between black and yellow, uniformly 

 throughout skin, coat and eye. The 

 effect is a brown. Again, increase in 

 intensity among the deepening factors 

 has a very direct relation to the eifect 

 of the agouti factor and suggests 

 titration of an increase in enzyme II 

 against an inhibitor. The width of the 

 yellow band of agoutis also increases to 

 some extent when black is changed to 

 brown or lilac but not to anything 

 like as marked an extent. Indeed, 

 Dunn has been able to produce brown- 

 and-tans in which brown takes the 

 place of black in black-and-tans. In 

 the first paper it was suggested that 

 such variations as black-and-tan could 

 be pictured as representing variations 

 in the actual quantity of a specific 

 enzyme for the production of dark 

 colors, while in browns and lilacs there 

 is no reduction in the quantity to be 

 titrated against inhibiting agents, but a 

 reduction in potency of some other kind 

 so that pigment is produced intermediate 

 in character between black and yellow 

 Such variations are put in class 2b. 



The Marriage Rate of the Insane 



The marriage rate of the insane is 

 discussed by Dr. A. Myerson, patholo- 

 gist of the Taunton State Hospital, in 

 in the January, 1917, issue of the Ameri- 

 can Journal of Insanity. Basing his 

 conclusions on a study of 663 families, 

 he finds that the female insane and the 

 general jjaretics, both male and female, 

 marry in slightly less i)roiJortion than 

 does the general jjoj^ulation. Alcoholic 

 males marry in much reduced ratio. 



while alcoholic females marr\- in nearly 

 normal ratio. It is to the dementia 

 praecox group that marriage offers the 

 greatest difficulty, for here both the male 

 and female ratios are very low and the 

 former, the male rate, is only about 

 one-half the latter, the female rate. To 

 some extent, then, all tyi)es of mental 

 abnormality act as barriers to repro- 

 duction, but in the female sex the 

 hindrance is very slight. 



3" Durham, F. M. 1911. Loc. cil. 



«i Little, C. C. 1913. Cam. Inst. Wash. Pub., 1 79: 1 1-102. 1916. .1 mcr. Xat., 50: 335-.U9. 

 " Dunn, L. C. 1916. Amer. Nat., 50:664-675. 



"Cu(5not, L. 1905,1907. Loc. cit. Durham. 1908. Loc. cil., etc. 



"Cu(^not, L. 1907. Loc. cit. Darliishire. 1904. Loc. cil. Castle and Little. 1909. 

 Sci.N.S.,30Jl3-3H. Plate, 1910. Zoo/. yl«z., 35:634-640. Durham. 1911. Loc. cit., etc. 



