38 



MASS STUDIES IN BUILD. 



parents is 34.86) and the corresponding departure of their offspring 

 from mediocre build (which for the progeny is 35.24). In the right- 

 hand column of the table is given the difference between these two 

 departures, which measures the amount of regression toward medi- 

 ocrity on the part of the progeny. The results of the last column are 

 shown graphically in figure 8. 



Table 15. — Average build and regression from parental average of the progeny of the various 

 types of mating. Also matings arranged in order of regression. Sexes combined 

 (based on table 12). 



Mediocrity for parents, 34.86. Mediocrity for progeny, 35.24.. 



Matings Arranged in Order of Regression. 



Figure 8 shows clearly that, in spite of considerable irregularities, 

 the line of regression descends from the matings of two very fleshy 

 parents at the left, and in general from matings in which the average 

 parental departure from the mean build of parents is positive, to the 

 mating of two slender parents (or, less strikingly the VS X S mating) 

 or in general to the matings in which the average parental departure 

 is extremely negative. This result is most easily explained on the 

 ground that whereas fleshy parents carry all sorts of gametes for 

 build, slender parents carry a preponderance of gametes of their own 

 kind; hence the progeny do not regress so much from the selected 

 parental condition. This suggests that the slender parents are more 

 nearly homozygous than the fleshy parents. 



