No. 530] 



THE MENDELIAN RATIO 



105 



where 



k. 



V2a 2 b + 288(a 2 6) 2 



a = quotient of twice the second moment divided 



by the third moment. 

 b = second moment. 

 Writing c for 



Since for a vanisliinglv small value of the third moment, 

 ab will be a very large number, consequently x/ab will 

 be infinitesimal. Tims neglecting all terms in which x/ab 

 is factor, we have 



Eestoring the value of C and remembering that for large 

 values of ab, k reduces to unity, we finally have 



which is t lie familiar formula for the normal probability 

 curve. 



From the above it is clear that DeForest's formula and 

 its limiting case represent the frequency distribution of 

 the zygotes, whether we are dealing with alternative or 



h\ -lirh 



we have 



■««(*)-(«* 



