THE MUTABLE UNIT OF HEREDITY 



55 



Table 2.3 shows a sample of such mutation rates. They range in bac- 

 teria, for example, from 10"'' to lO'* per cell per division. But we 

 realize that these rates are simply the chance with which the pheno- 

 typic change is observed. Even if all these mutations were point muta- 

 tions, we would not know in any particular case whether one or many 

 mutable units were involved. Therefore we expect variation in the 



TABLE 2.3 

 A Sample of Spontaneous Mutation Rates in Different Organisms 



(Character Rate I'nits 



Organism 



* Correction of the other mutation rates in this table to a per-gene basis would not 

 change their order of magnitude. 



