MUTATION. 



309 



I maintain, therefore, that ''mutation" is not a special kind of variability, 

 different from that of ''ordinary fluctuating variation," but it is a part of the 

 normal variability, and the direct response of the germ plasm to stimuli. This 

 is fully borne out by the data and experiments with Leptinotarsa. This, how- 



Range of ** normal fluctuating variability.'" 













1 Mean of species. 



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Text -FIGURE 31.— To show the distribution of inheritable variations about the mean of 

 L. dccemlineata. p = L. pallida; d=L. defectopuv data ; n = Z. minuta; i=L. immac- 

 ulothorax: m = L. melanicum; = L. obsolefa; t = L. iortuosa; r = L. rubrivittata. 



