The Origin of the Markings of Caterpillars. 349 



definition. Now it might be difficult to attribute 

 any biological significance to this character, but its 

 origin becomes clear on examining light specimens 

 in which the oblique white stripes are distinct on 

 the sides and the subdorsal line is retained at 

 least on the five or six anterior segments. It can 

 then be seen that the spots are located at the 

 points of intersection of the subdorsal and the 

 oblique stripes (Fig. 16, PL III.), and they can 

 accordingly be explained by the tendency to the 

 deposition of light pigment being twice as great 

 in these positions as in other portions of the two 

 systems of light lines. Light spots are thus 

 formed when the lines which cross at these points 

 are partially or completely extinct throughout 

 their remaining course. 



A marking is therefore produced in this case by 

 a purely innate law of growth by the superposi- 

 tion of two ancient characters now rudimentary. 

 Many other unimportant details of marking must 

 be regarded as having been produced in a similar 

 manner, although it may not be possible to prove 

 this with respect to every minute spot and stripe. 

 The majority of " subordinate markings " depend 

 on the commingling of inherited, but now mean- 

 ingless, characters with newly acquired ones. 



It would be quite erroneous to attribute to 

 natural selection only those characters which can 

 be demonstrated to still possess a biological value 

 in the species possessing them. They may be 



