198
POPULAR SCIENCE MONTHLY.
hypophylangia (two-jointed instead of three-jointed digits) is dominant over the normal condition. In mice, the peculiar waltzing habit of so-
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/28/PSM_V67_D204_Guinea_pig_with_short_smooth_pigmented_coat.png/510px-PSM_V67_D204_Guinea_pig_with_short_smooth_pigmented_coat.png)
Fig. 6. A Guinea-pig with Short, Pigmented Coat. Its parents were the animal shown in Fig. 4 and one like that shown in Fig. 5.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/86/PSM_V67_D204_Guinea_pig_with_long_smooth_albino_coat.png/510px-PSM_V67_D204_Guinea_pig_with_long_smooth_albino_coat.png)
Fig. 7. A Guinea-pig with Long, Smooth, Albino Coat. These three characters are all recessive in nature.
called Japanese mice is a recessive character in heredity. In man, a peculiar dark-colored condition of the urine, known as alkaptonuria, is