22 



INHERITANCE IN GUINEA-PIGS. 



on board our steamer during a stop made in the night at Pisco, the 

 terminus of the short line of railway which leads down from lea to the 

 coast. I found them the next morning in the "butcher-shop," con- 

 signed from lea to W. R. Grace & Co. in Callao. I conclude that they 

 really did come from the neighborhood of lea. (2) I saw no domesti- 

 cated guinea-pigs in Peru which were self-colored like these animals. 

 All domesticated ones which I saw in Peru, except albinos, were spotted 

 with white, or with yellow, or both. Self varieties are not fancied in 

 Peru. Varieties of this sort are not uncommon among the guinea-pigs 

 kept by European and American fanciers, but apparently they have 

 been established only by careful and long-continued selection from the 

 pied stock originally introduced from South America. (3) The spotting 

 and the rough character which have cropped out as recessives among 

 the descendants of the three lea animals are feebly expressed characters 

 which appear to have been almost obliterated, but which still come to 

 expression feebly under inbreeding. This is what we should expect 

 to find in a feral race acted upon by natural selection, conspicuous 

 variations like spotting tending to disappear. 



TABLE 13. Parentage of pure lea animals whose matings are recorded in table 12. 



Original stock. 



The 3 original lea animals or their inbred descendants mated inter se 

 have produced 114 young, of which 62 have been golden agoutis, 49 sil- 

 ver agoutis, and 3 blacks.; 4 of the 114 have shown a small amount 

 of white spotting, 3 have shown yellow spotting, and 1 has shown a 

 small amount of roughness of the coat. 



The various matings which have produced these young are classified 

 in three groups in table 12, and the parentage of each animal which 

 took part in a mating is shown in table 13, from which pedigrees may 

 readily be drawn tracing back to the original trio. It will be observed 

 from table 12 that silver agouti was derived from golden agouti as a 

 recessive and has bred true without exception (31 silver agouti young 

 being produced by silver agouti parents). 



