106 Experimental Zoology 
guinea pigs was produced, which compared favorably with the 
intermediate groups described above. Crossed with long-haired 
individuals two kinds of offspring were produced, with long and 
intermediate hair, but with no definite line of separation. 
Experiments with Rabbits 
Hurst has carried out a series of experiments with rabbits that 
have given results of unusual interest, especially in connection 
with the inheritance of color and of length of hair. Two races 
that were known to breed true were used, namely, white An- 
goras and Belgian hares. The former is an albino breed with 
pink eyes and silky hair. These animals have a peculiar habit 
of swaying the head when at rest. The Belgian hare has a pig- 
mented skin, dark eyes, and short yellow-gray fur. When crossed 
the hybrids were pigmented like the Belgian hares, but the hair 
had lost the yellow color and was gray, like that of the common 
wild rabbit. When these first hybrids were inbred they produced 
14 distinct types in the second generation, viz. : — 
Hair short, pigmented, gray, uniformly colored. 
Hair short, pigmented, gray, marked. 
Hair short, pigmented, gray, Dutch marked. 
Hair short, pigmented, black, uniform. 
Hair short, pigmented, black, marked. 
Hair short, pigmented, black, Dutch marked. 
Hair short, albino, white. 
Angora, pigmented, gray, uniform. 
Angora, pigmented, gray, marked. 
Angora, pigmented, gray, Dutch marked. 
. Angora, pigmented, black, uniform. 
12. Angora, pigmented, black, marked. 
13. Angora, pigmented, black, Dutch marked. 
14. Angora, albino, white. 
DO MW AT AY vo 
ee 
H 
This “ epidemic of variation” in the second generation of hybrids 
has been the common experience of experimenters both in ani- 
mals and plants, and before the Mendelian principles became 
