88 



The Journal of Heredity 



chestnut to a faded liver color, and 

 reds vary from mahoj^any to lemon. 

 The case of blue Mcrled Collies has 

 been noted above. The kind of dilution, 

 which has been most thorouj^hly in- 

 vestij^ated, is that of the imperfect 

 albinos, which occasionally appear in 

 Pekinese Spaniels. Pearson, Nettle- 

 ship and Usher describe extensive ex- 

 periments with them. 



ALBINO PEKINESE SPANIELS 



Their albinos came from a stock of 

 red Pekinese. Most of them were not 

 complete albinos, but were slightly 

 tinted with cream color. The skin was 

 pink, the iris pale blue, and the pupil 

 red in some lights. The coat was 

 often distinctly colored, in the pvippies, 

 with a dull brown color, which might 

 show a distinct piebald pattern. Granu- 

 lar pigment was present in these puppies, 

 but in the adults only traces of diffuse 

 pigment could be found, as a rule. 

 This change in color is parallel to a 

 change in the normal red Pekinese 

 Spaniels, whose coats are brown, tipped 

 with black, as puppies, but turn red 

 later, only the face and scattered hairs 

 on the back retaining the dark color. 

 The mode of inheritance seems clearly 

 that of a single recessive factor. The 

 authors arc disposed to question any 

 Mendelian interpretation, but this is 

 largely because they consider the pie- 

 bald pattern, which appeared irregularly 

 through their experiments, as connected 

 with albinism, and because of compli- 

 cations, due to the introduction into the 

 experiments of a second well known 

 Mendelian factor: that in which blacks 

 are dominant over reds. 



Although coming from a colored 

 stock, the albinos bred true at once, 

 (except for minor variations). Albino 

 by albino produced 66 allnnos, of which 

 11 were decidedly brown as puppies, 

 and 2 were recognizable piebalds. Red 

 parents, both of which were known to 

 carry albinism, from knowledge of their 

 parents or offspring, produced 32 red, 

 and 14 albino pupj^ics, about as ex- 

 pected, allowing for matings of their 

 type which were unrecognized because 

 no alh)inos were produced. Red by 

 albino produced only 57 reds in 16 



litters, and 5 reds, 4 albinos in 2 other 

 litters. Most of the reds were evidently 

 homozygous. vSome of the albino Peki- 

 nese were crossed with black Pomera- 

 nians. As these albinos came from red 

 stock, this cross would be expected to 

 involve at least two Mendelian factors; 

 that by which blacks differ from reds, 

 and that by which intense colored dogs 

 differ from albinos. In Fi all of the 

 puppies were intense, and most of them 

 black. Two of the 17 were called 

 chocolate, which indicates that the 

 Pomeranians were not all homozygous 

 black. Some of the black offspring 

 (EeCc) were crossed together and pro- 

 duced 6 blacks (with white patches), 

 1 red sable, like a normal Pekinese, 1 

 normal albino and 1 permanently slate- 

 brown or "lilac" puppy, with the eyes 

 of an albino. One need have little 

 hesitation is surmising that this "lilac" 

 is the albino form of black (Ecc) where 

 the usual Pekinese albino is the albino 

 form of red (eecc). A back cross of Fi 

 black with Pekinese albino likewise pro- 

 duced the four expected classes. There 

 were 10 blacks, 2 golden sables, 1 

 "lilac," and 2 usual albinos (one of 

 which showed a red streak on its back). 

 The ratio, it is true, is very aberrant; 

 such a large excess of blacks should be 

 produced only once in a thousand 

 times, but taking the evidence as a 

 whole, there seems little reason for 

 doubting that merely two unit Men- 

 delian factors are involved aside from 

 the factor or factors for the ])iebald 

 pattern. It has been suggested above 

 that the albino factor which reduces 

 red to white merely reduces black to 

 slate-brown. This is in harmony with 

 the brown color of Pekinese albinos at 

 the time of life in which nonnal reds 

 show much black pigincnt. It is also 

 thoroughly in hannony with the effects 

 of imperfect albinism in other mammals. 

 The same difference in the threshholds 

 for black and red, with respect to al- 

 binism, have been noted in previous 

 papers in the discussion of red-eyed 

 dilute guinea-pigs and rats, and Hima- 

 layan rabbits. A similar phenomenon 

 is found in man. 



Among factcirs of class 2, it seems well 

 established tliat all grades of red differ 



