SYNTHETIC PINK-EYED SELF WHITE 

 GUINEA-PIGS^ 



DR. HEMAN L. IBSEN 

 Introduction 



In the fall of 1914 Professor W. E. Castle kindly sent 

 to the Department of Experimental Breeding, Univer- 

 sity of Wisconsin, five gninea-pigs re])resentiiig some of 

 the rarer color varieties, snggesting that their genetic 

 make-np be studied independently. These animals wore 

 sul)sefinently turned over to the writer for investigation. 

 During tlie winter two of them died without offspring 

 and hence only tliree were left the following spring. 

 Two of these proved to he what has been called by Castle 

 red-eyed agoutis and the third was a pink-and-red- 

 oyed" tortoise. The factors involved in the production 

 of these animals will be descri1)od below in more detail. 



(^astle (1914) had already (U-scribcd tlie different fac- 

 tors found in these aninuds niid lind uivcn some indica- 

 tion of their relationships to other tactoi's. At this 

 time he stnli'd tliat rcd-excd was a Mclomorphic to al- 

 binism, and lhal ])ink-('y('(l was i-cccssive to the usual 

 (lai-k-cycd con. lit ion. In 19 IT) \Vi'i-ht showed that red- 

 e\«'(l formed an alh'h)mori»hic series with albinism and 

 dilute and inlcnsc ))igmentation. This made the account 

 of the relationships of the factors fairly complete. 



At alxuit this time it occurred to the writer that with 

 the projx'r eoml)ination of the newly described factors 

 and otlier factors it should be possible to produce an ani- 

 mal which to all appearances would be an ordinary al- 

 bino, 1)ut entirely different geneticallv fi'om what have 

 hitherto })een known as albinos. Matin-s w,mv inmie- 



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