PHENOMENA OF INHERITANCE 225 



good fortune if he begets a son who is as 

 richly endowed as himself." This so-called 

 law of filial regression is represented graphi- 

 cally in Fig. 47 in which the actual stature 

 of individual parents is shown by the oblique 

 line, the stature of children by the dotted 

 curve, and the mean stature of the race in the 

 horizontal dotted line. 



One of the chief aims and results of statis- 

 tical studies is to eliminate individual peculiari- 

 ties and to obtain general and average results. 

 Such work may be of great importance in the 

 study of heredity, especially where questions 

 of the occurrence or distribution of particular 

 phenomena are concerned; but the causes of 

 heredity are individual and physiological, and 

 averages are of less value in finding the causes 

 of such phenomena than is the intensive study 

 of individual cases. 



By observation alone it is usually impossi- 

 ble to distinguish between inherited and en- 

 vironmental resemblances and differences, and 

 yet this distinction is essential to any study 

 of inheritance. If all sorts of likenesses and 

 unlikenesses are lumped together, whether in- 



