Some Characters in Human Beings 



41 



shorter than normal, and minor streblomicrodactyly (Fig. 14) , in 

 which the little fingers are bent. Symphalangism, or the fusion 

 of the phalangeal joints of the digits, is a character caused by 



Fig. 14. Crooked little fingers (minor streblomicrodactyly). The ab- 

 normality is especially noticeable in side view. (Courtesy of Dr. R. A. 

 Hefner in the Journal of Heredity.) 



a dominant gene. Strandskov has reported a case of the in- 

 herited absence of thumbnails. This character is probably the 

 result of a dominant gene, although the number of cases is too 

 few for certainty; it is generally accompanied also by a slight 

 abnormality of the nails on some of the other fingers. 



