EXERCISE 94 



ARE VARIATIONS IN PARENTS TRANSMITTED TO OFFSPRING? 



Materials. The table given below shows the height of 928 persons whose records were studied 

 by Francis Galton. It is so arranged that the heights of these individuals may be compared with the 

 heights of their parents, and the inheritance of stature may thus be seen. 



Directions. In the third horizontal space from the top the figures given indicate the size-groups 

 in which the children are classified. The vertical column at the left (column 1) gives the heights of 

 the parents, the heading " mid-parental height " meaning the middle point between the heights of the 

 two parents in a family. 



In column 16 at the right the figures in each space represent the average height of all children 

 of parents of the heights indicated in the corresponding space in column 1. The other figures of the 

 table indicate the distribution of the children. The way in which the table is read is indicated by 

 the following examples: 



Column 3 shows that among the seven persons whose heights were near 62.2 inches there were 

 three from families in which the mid-parental height was 67.5 ; three from families with a parental 

 average of 66.5 ; and one from a family in which the parental average was 64.5. 



Line b shows that in all the families in which the mid-parental height was 72.5 inches one 

 child had a height, when adult, of about 68.2 inches; two were 69.2 inches tall; one was 70.2; 

 two were 71.2 ; seven belonged to the 72.2 group ; two belonged to the 73.2 group ; and four were 

 taller than any of these. 



Examine line f. Observe and state how wide is the variation. Note how many children are 

 taller than their parents, how many are shorter, and how many are nearly of the parental height. 



[138] 



