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 of 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 
La wR eg AN a 
Fic. 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 
