Inheritance of Qua ntita live Characters 



75 



ent groups on the basis of degree of redness. Applying 

 the same conception as before, Nilsson-Ehle discov- 

 ered that in this case he was dealing with a trihybrid 

 situation. Without constructing the usual Mendelian 

 checkerboard, which would have to be extensive enough 



Pure Red 



VVKite 



Grades of Pink 



Fig. II. — Another method of visualizing Nillson-Ehle's 15:1 

 ratio (see fig. 10). 



for 64 individuals, the situation as it appeared in the F2 

 generation may be represented by lig. 12. If this graph 

 be surmounted by a cur\'e, we recognize the regular 

 "probabilities curve," exactly the kind used by biome- 

 tricians to represent fluctuating variations about a specific 

 type. 



