SEGREGATION IN 1IEREDIT1 . 





35. Where the mode is at 33 it is probable that an Sand an M gan 



have met; and this condition is relatively common just I •• ■ M 



gametes are common. The mode at 35 may arise from an 1 gan 

 carried in a heterozygous M uniting with an S gamete. The - 

 carried in heterozygous M may be responsible for a probable ra 

 which is hidden in the form of a hump at 28 in figure 52. 



Attention is called to the probable influence of these modes on the 

 two modes shown in figure 7, at 33 and 35 respectively. These two 

 modes are strong evidence for a segregation in the factors for build. 

 Thus the very irregularity of the polygon of figure 7 is evidence of He- 

 presence of segregating factors for build. Moreover, these two mi 

 appear at every age from birth to maturity, as is clearly shown in 

 figure 53. This bimodality is easily accounted for on genetics] 

 grounds, but is inexplicable upon the bare nutritional hypothesis of 

 build. 



On the Number of Factors Involved in Fleshy Build. 



It is by no means an easy matter to determine the number of inde- 

 pendent factors which are active in the case of a trait that is due to 

 multiple factors. This matter is still less easy if there is only very 

 imperfect dominance approaching intermediacy of the trail in tie- 

 progeny of the Fi mating. Yet that is the situation that has to be 

 met in the study of heredity of build. 



An attempt has been made in this paper to test the relative prob- 

 ability that there are only two, on the one hand, or three or more 



Fio. 51.— Polygon of distribution of offspring of M X F n i UbU XI), 



sexes separate and combined. See also 1.k'> A t I ■ 



