No. 579] ALBINO SERIES OF ALLELOMORPHS 



143 



tives from the series, never more or less, which two may, 

 of course, be alike. Thus with dominance in the order of 

 increasing pigmentation intense guinea-pigs should be 

 homozygous, or else carry recessive dilution, recessive 

 red-eye or recessive albinism, but never more than one of 

 these ; dilute guinea-pigs should be homozygous, or carry 

 recessive red-eye or recessive albinism, but never both; 

 red-eyes should be either homozygous or carry recessive 

 albinism; and finally albinos should always be homozy- 

 gous and never have the power of transmitting intensity, 

 dilution, or red-eye to their descendants. All of these 

 types have been obtained and tested with results in har- 

 mony with expectation. In this paper only a few of the 

 most critical crosses will be given, reserving a more de- 

 tailed discussion for a later paper. 



Eed-eye, as mentioned before, has occurred only in the 

 descendants of certain pigs brought from Peru. No al- 

 binos appeared in the pure stock. In the pure races, red- 

 eye behaved as a simple recessive. Thus intense by in- 

 tense gave 63 intense and 19 red-eye young, while red-eye 

 by red-eye gave only red-eyes, 28 in number. 



As red-eyes had never appeared in our stock guinea- 

 pigs, it was natural to expect that any stock pig crossed 

 with red-eye, an apparently recessive condition, would 

 give only intense young. As a matter of fact, however, 

 numerous red-eye young appeared in F x . The next ques- 

 tion was whether one kind of stock differed from another 

 in its power of bringing about this apparent reversal of 

 dominance. A study of the records soon showed that 

 albinism had something to do with the matter, as the fol- 

 lowing tabulation indicates : 



Red-eye X intense ^'ST ^22* * ^20° 



Red-eye X albino 80 32 



The difference in result of the two sorts of matings is 

 obviously significant. With an intense parent there were 

 more than 50 per cent, intense young and comparatively 

 few red-eye young. With an albino parent there were no 



