Experiments with other Mammals 103 



in some cases may be slow, in others sudden, so that the inter- 

 mediate steps are passed over at once. 



Heredity 0} the Long Coat. A race of long-haired cavies is 

 known, either smooth (Angoras) or rough (Peruvians). The 

 two sets of characters, long versus short, and smooth versus 



Ui. 



FIG. 8. Upper figure, long haired, smooth coat albino guinea pig. Lower 

 figure, short-haired, rough coat, black-red pigmented guinea pig. (After Castle.) 



rough, are independent of each other in their behavior in heredity. 

 The long-haired is recessive in relation to the short-haired or 

 ordinary types. The long hair is not present at birth. The coat 

 of the short-haired guinea pigs reaches its maximum length 

 (about 4 cm.) not far from the age of one month, and is then 

 gradually shed and renewed. On the other hand, the hair of the 

 long-coated animals is apparently not shed at this period, but 



