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 Lcptinotarsa. This, how- 



Range of " normal fluctuating variability.' 



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

 L. dccemliueata. p = L. pallida; d = L. defectopuvctata: n L, minuta; i=L. immac- 

 ulolhorax ; Tft = L. melanicum; o = L. obsolefa; t = L. tortuosa; r = L. rubrivittata. 



