PHENOMENA OF INHERITANCE 197 



ever, his statistical and mathematical formulae 

 give only general or average results, from 

 which there are many individual departures 

 and exceptions. 



In the same way the color of the skin, the 

 color and form of hair and the color of eyes 

 are in general like those of one or more of 

 the parents or grandparents. We all know 

 that certain facial features such as the shape 

 and size of eyes, nose, mouth and chin are 

 generally characteristic of certain families. 



But the inheritance of anatomical features 

 extends to much more minute characters than 

 those just mentioned. In certain families a 

 few hairs in the eyebrows are longer than the 

 others, or there may be patches of parti- 

 colored hair over the scalp, or dimples in the. 

 cheek, chin, or other parts of the skin may oc- 

 cur, and these trifling peculiarities are in- 

 herited with all the tenacity shown in the 

 transmission of more important characters. 

 Johannsen has foimd races of beans in which 

 the average weight of individual seeds differed 

 only by .02 to .03 gram, and yet these minute 

 differences in weight were characteristic of 



