196 



The Mechanism of Evolution in Leptinotaksa 



It is only in one very trivial aspect, however, that the clifEerences in spot c con- 

 form to "^this condition, as has been shown in the three sets of examples given. 

 Area in this character is not necessarily quantity of pigment, but area of surface 

 pigmented, and can not show truthfully either the quantity, process, product, or 

 distribution in either materials, duration of processes of pigment development, 

 or relations to adjacent parts. 



o — — 



o — — 



Fig. 16. — Area of 500 left c spots in 

 L. multitwniata from Puebla. 



Fig. 17. — Area of 500 left c spots in 

 L. muUitwniata from Guadalupe. 



If the distribution of the pigment in the spot c is considered, and not the 

 amount of pigment, it appears that there are several directions of change in the 

 distribution of pigment and in relation of these to the other centers of coloration. 

 Is it the amount of the pigment, the area colored, that is important, or is it the 

 arrangement and changes in arrangement and relation to adjacent parts that 

 are important? Spot c presents two distinct sets of "variation" data, of 



Fig. 18. — Showing difference in size, shape, and direction of 

 variation in spot b in L. utidecimlineata. 



which the relative importance is entirely dependent upon one's initial philo- 

 sophical viewpoint, upon definition. Other similar areas of pigmentation 

 on the animal show identical conditions in principle and confirm in every 

 way the statement made. Different manifestations of spot h on the prono- 

 tum of L. undecimlineata are represented in figure 18, and show that the 



