November 7, 1907J 



NA TURE 



Indian characters appear to be dominant over the corre- 

 sponding allelomorphs of the European. This conclusion, 

 however, receives corroboration from the results of 

 marriages between Europeans and three-quarter blood 

 Indians, when they are traced to the F, generation. 

 There is thus no blending, even of colour, but dominance. 



We can now deal with the important question of segre- 

 gation. If segregation occurs in man, and we regard 

 these f.ve characters (the beard is excluded) as allelo- 

 morphic pairs, then when a half-breed Indian (that is, the 

 child of a European and Indian marriage) is mated with 

 a European we should expect, a»ion^ others, to find the 

 following types in the offspring : — 



(i) Wholly Europeat., EH, EE, ES, EC, EN. 



(2) Wholly Indian, iH, IE, IS, IC, IN. 



(3) European except in the cheek-bones, EH, EE, ES, 

 IC, EN. 



(4) European except in the eves and cheek-bones, EH, 

 IE, ES, IC, EN. 



(5) Indian except in the nose, IH, IE, IS, IC, EN. 



(6) Indian except in the hair, EH, IE, IS, IC, IN. 



(7) Indian except in the skin and nose, IH, IE, ES, 

 IC, EN. 



And all these predicted seven types are to be found in 

 the records of four marriages between an E and \ I which 

 have been sent to mc. A total of seventeen children are 

 considered in this description. 



It is perfectly clear that segregation of these five 

 characters is taking place. There is no blending even of 

 the colour of the hair, eyes, or skin. The blue eyes of a 

 Scotchman who was mated to a full-blood Indian, and 

 whose wholly Indian-type hybrid was mated in turn to a 

 Welshman of hazel eyes, came out blue in two members 

 of an offspring of eight children in the F, generation. 

 That is clearly enough segregation. 



If segregation is really occurring, and if the Indian 

 features are dominant over the European, then it follows 

 that once a pure European type has separated out and 

 is mated with a European, Indian features ought not 

 to appear among their offspring. In the records which 

 I have there are two marriages of this kind, i.e. between 

 E and extracted E. From one of these there have resulted 

 five daughters, and from the other a son and a daughter. 

 W\ seven are European in every trait. The recessive 

 characters have thus far bred true. 



These facts, therefore, are not only opposed to Dr. 

 .\rchdall Reid's statement that there is no segregation in 

 mankind, but they supply him with that instance of an 

 appearance of a " latent '* character in a cross between 

 two " natural varieties " as contrasted to " artificial 

 varieties " for which he seeks. For I suppose he will 

 regard (if I may judge from the context of his letter) a 

 cross between an Ex J I, followed by a cross of Ex ex- 

 tracted E, as crosses between natural varieties. At any 

 rate, they are crosses between human varieties, and he 

 denies rather too emphatically that " latent " characters 

 have ever been revealed in such. 



Dr. Archdall Reid is apparently not aware of Farabee's 

 observation on the mating of albino negroes with pig- 

 mented negresses. The facts are important, so perhaps T 

 may describe them. An albino negro married a normal 

 negress. They had three children, all pigmented sons. 

 These sons married, and two of them had only norma! 

 ''pigmented) children ; but the third son married twice, 

 and by the first wife had five normal and one albino 

 .'hildren, and by the second si.x normal and three albino 

 children. If we assume that the two negresses which the 

 third son married were themselves carrying albinism re- 

 cessive (that is, in Dr. .Archdall Reid's sense of the word, 

 " latent "), the result is accurately in accordance, as 

 Castle has shown, with Mendelian expectation. For, in 

 the offspring of this third son, coloured individuals and 

 albinoes are expected in the proportion of 3:1. There 

 Is actually 11 : 4, which is the nearest possible approxim- 

 ation in an offspring of fifteen. 



If Dr. Archdall Reid can explain these results, i.e. those 

 of the Red Indians and the negroes, on anv other theory 

 than Mendelian segregation, or can even show that it is 

 a case of an abnormality of sexual reproduction which 

 occurs under conditions of " artificial selection," it will 

 be of the most entrancing interest. 



NO. 1984, VOL. ']']'\ 



It may, of course, be objected that the negro case is 

 one of the crossing of artificial and not of natural varieties. 

 To me such an objection presents itself as a play with 

 words. No one, I take it, will deny that if the condi- 

 tions of the Mississippi region were favourable to albinism 

 and unfavourable to pigmentation, a variety of albino 

 negro would arise as permanent in its characters as any 

 other natural variety of man. Besides, the albino case 

 must be read with that of the Canadian Red Indian, and 

 this is a natural variety as well as the European crossed 

 with it. Both cases lead to the same conclusion. 



Dr. Archdall Reid's doubt as to whether Mendelians 

 " are engaged in anything more than the investigation of 

 those abnormalities of sexual reproduction which occur 

 under conditions of artificial selection " therefore becomes 

 an assumption with an inadequate basis. 



Geo. p. Mudge. 



Biological Laboratory, London Hospital 

 Medical College, October 21. 



I HAVE already (Nature, October 31) dealt with muta- 

 tions, of which albinism is one. 1 have no first-hand 

 acquaintance with Red Indian half-breeds. In the case of 

 such characters as skin-colour and shape of nose and cheek- 

 bones, even "when well developed," "the personal equa- 

 tion of the observer and the precision of his categories " 

 have sometimes to be reckoned with. Having regard to 

 the -Mendelian doctrine of the independent inheritance of 

 characters, does it not strike .Mr. Mudge as singular that 

 in the only example he possesses of marriages between 

 E and extracted E all the offspring should be " European 

 in every trait "? If his correspondent is correct, the Indian 

 half-breed of the F, generation is " quite " indistinguish- 

 able from the full-blooded Redskin. I venture to appeal 

 to readers of Nature who have first-hand acquaintance 

 with the facts. The information we need is not whether 

 exceptional half-breeds of the F, generation resemble pure- 

 bred Indians, but whether this resemblance is the rule. 

 Personally, I have a fairly large and close acquaintance 

 with the half-breeds of Europeans on the one side, and 

 negroes, Maoris, Kanakas, and several Asiatic races on 

 the other. To my eyes, except in eye-colour, they are 

 clearly distinguishable as half-breeds, though variations 

 occur, and the dark race is sometimes approached rather 

 closely. The case of eye-colour is remarkable. The black 

 persists until one or more infusions of north European 

 blood occur, when the light-coloured eye suddenly appears. 

 So far as I am able to judge, though here I cannot speak 

 with any degree of certainty, the quickness of the re- 

 appearance of the light eye bears a relation to the degree 

 of pigmentation of the dark race ; that is, fewer infusions 

 from the light-eyed race are required when it is crossed 

 with the black-eyed European type than when it is crossed 

 with the -Asiatic, and more especially the negro. W'hatever 

 all this indicates — and I think I know, though lack of 

 space forbids any attempt to entrance Mr. Mudge — very 

 obviously it does not indicate Mendelian segregation. By 

 latent characters I meant those long-lost ancestral traits 

 which re-appear when domesticated races of rabbits, mice, 

 pigeons, and the like are crossed. 



G. Archdall Reid. 



Newton's Rings in Polarised Light. 



In Nature of October 24 (vol. Ixxvi., p. 637) Mr. Edser 

 asks whether anyone has tried the experiment of Lloyd's 

 single mirror fringes with polarised light to see whether 

 a change of the character of the fringes would occur on 

 rotating the plane of polarisation of the light. Lloyd 

 tried the experiment himself with light polarised by trans- 

 mission through tourmaline, and observed no change in 

 the appearance of the fringes (Lloyd, " Papers," p. 156). 

 I have made the same experiment with Lloyd's fringes by 

 internal reflection, and found no effect on rotating a Nicol 

 prism through which the fringes were observed (Phil. 

 Mag., October, p. 507). 



The change of phase for grazing incidence is 7r, what- 

 ever be the plane of polarisation of the incident light. 

 The fringes, therefore, are of the same character for light 

 of all kinds. P. V. Bevan. 



Trinity College, Cambridge. 



