102 Experimental Zoology 
cattle have been able to do it seems not improbable that this 
might be accomplished. 
Castle draws attention to the curious point that red and yel- 
low cavies, having no black pigment in their coats, do not trans- 
mit black coat-pigment to their offspring, although they do 
transmit black eye-pigment. It would be erroneous, he thinks, 
to conclude from this that the eye-pigment is something alto- 
gether different in its inheritance from coat color, because when 
mice with coat patches but devoid of eye-pigment are mated 
with albinos, the offspring have pigmented eyes —a character 
that neither parent possessed 
Heredity of the Rough Coat. —Some races of domesticated 
guinea pigs show the hair arranged in whirls or rosettes. When 
best developed the rosettes are found around the following 
paired centers: (1) the eye, (2) a point immediately behind the 
ear, (3) the shoulder, (4) a point dorso-lateral on the body, 
(5) the hip, (6) the groin, (7) each of the single pair of mamma; 
and from two unpaired centers, viz. (8) the middle of the fore- 
head, and (9) the navel. The direction of the hair is also re- 
versed on the toes. 
These rough-coated individuals breed true. When crossed 
with smooth-haired individuals the rough character dominates. 
The rough character of the offspring is usually as fully developed 
as in the rough parent. However, certain smooth individuals 
when crossed bring about a weakened condition of the rough 
character, some of the rosettes being less developed or even 
absent. These partially rough individuals may transmit to 
their descendants the fully rough condition. The result is 
important in that it shows that what we must regard as a new 
character in the species, yiz. a rough coat, dominates when a 
back cross is made.t On the other hand, Castle has also found 
that repeated crossing of rough individuals with prepotent smooth 
ones results in further weakening of the rough character until it 
is almost eliminated — one after another of the rosettes disap- 
pearing. The weakening does not follow a definite decline, but 
* See Castle’s analysis, pp. 47-50. 
