WARNING COLORS, WITH EXAMPLES 159 



in the direction of the caudal horn. The oblique stripes became 

 lengthened toward the back, the longitudinal lines disappeared 

 since they injured the deceptive effect of the stripes. In many 

 species there were also formed dark or variegated colored edges 

 to the oblique stripes, in imitation of the shadow lines cast by 

 the leaf ribs. Still others, of the longitudinally striped species, 

 became developed in another manner. 



The first ring-spots probably arose on the next to the last 

 segment and after a time became repeated on the other seg- 

 ments, advancing from the hind segments toward the front 

 ones. If a caterpillar fed on plants containing acrid juices 

 which rendered it repulsive to other animals, the ring-spots 

 commencing to appear would furnish an easy means for natural 

 selection to adorn the species with brilliant colors, which would 

 protect it from attack by acting as signals of distastefulness. 

 But if the dark spots stood on a light ground, they would present 

 the appearance of eyes and cause their possessors to appear 

 alarming to smaller foes. Weismann believes that in the case 

 of the three chief elements of the markings in the sphinx- 

 moths, the initial stages, as well as their ultimate perfection, 

 are of decided advantage to their possessors, and that they can 

 be traced to the action of natural selection, and from the 

 fact of their evolution these changes were not without exerting 

 a certain action on other parts or an innate law of growth, 

 which Darwin called correlation. 



