INHERITANCE IN ORGANISMS 



565 



production of an excessive amount of urine; hereditary night bhndness; 

 congenital cataract; and the presence of extra digits or of short digits on 

 either hands or feet. Among the recessive defects, aside from feeble- 

 mindedness, are those of dwarfness and certain types of nerve degenera- 

 tion causing paralysis. 



Fig. oS8. — Small eyes in four successive generations of the same family. I, the great- 

 grandmother. II, son of I. Ill, the daughter of II. IV, the daughter of III. {Photo- 

 graphs by Whitney.) 



For every abnormal character inherited, there is its allelomorphic 

 normal character inherited, but many normal characters have no known 

 allelomorphic abnormal mates. In man only a few abnormalities are 

 inherited, whereas there are great numbers of normal traits inherited. 

 Among these are eye, hair, and skin color; size of eyes (Fig. 388); form 

 of hair, whether kinky, curly, wavy, or straight; number of fingers and 



