The Origin of the Markings of Caterpillars. 277 



age of the organism may, when advantageous, be 

 inherited by the succeeding generations, in such 

 a manner that they always appear a little earlier 

 than in the preceding generations." 



It is certainly theoretically conceivable that a 

 newly acquired character, when also advantageous 

 to the earlier stages, might be gradually transferred 

 to these stages, since in this case those individuals 

 in which this character appeared earliest would 

 have the greatest chance of surviving. In the 

 case of the development of larval markings, how- 

 ever, there are facts which appear to me to show 

 that such backward transference of a new character 

 is, in a certain measure, independent of the prin- 

 ciple of utility, and that it must therefore be re- 

 ferred to another cause to the innate law of 

 growth which rules every organism. 



When, in the larva of C. Elpenor, we perceive 

 that the two eye-spots which are first formed on 

 the fourth and fifth segments appear subsequently 

 on the other segments as faint traces of no bio- 

 logical value whatever, we cannot explain this 

 phenomenon by natural selection. We should 

 rather say that in segmented animals there is a 

 tendency for similar characters to be repeated on 

 all the segments ; and this simply amounts to 

 the statement, that an innate law of growth is 

 necessary for the repetition of such newly acquired 

 characters. 



The existence of such a law of growth, acting 



