No. 631] 



FACTORS OF HEREDITY 



109 



large relative deviations of the linkages as compared 

 with each other— this is particularly true the smaller the 

 absolute per cents of separation are— and so a totally 

 erroneous impression of the nature of the linkage system 

 may be produced. The nature of the linkage system— 

 whether it is linear and, if so, what function of a line is 

 involved— can only be studied to the best advantage in 

 experiments involving several factors at the same time, 

 but if our judgments regarding it have already been ar- 

 rived at, or verified, in this way, it is then quite legitimate 

 to use this knowledge for other factors, and to join the 

 results of different experiments involving them into one 

 linear map. 



TABLE II 



Factors y, bi, cl, v, s, B, as shown in a Count op 712 Flies from 

 a Cross in which Twelve Sex-linked Factors were 

 Followed Simultaneously. (Muller) 



Dependent on five f , g o 96 ! 41 6 y v + v B - 350 49.2 



In the experiments previously cited, the nature of the 

 linkage in various sections of the chromosome has been 



