2IO KELLOGG AND BELL 



antennae, eyes, auditory organs) to the habits of the insect, of 

 the size or shape or number of special parts to direct needs on 

 their part of adaptation to environing conditions, and by other 

 such relations between the conditions of life and the developing 

 organism. 



An important one of these special environing conditions of 

 life, and one that certainly works direct and apparent influence 

 on the body wall of certain animals, is what may be called the 

 chromatic condition of the environment. Color and pattern 

 adapted to the needs of protection or aggression are phenomena 

 familiar throughout the animal series. Most of such color and 

 pattern conditions, catalogued under the heads of protective re- 

 semblance, mimicry, warning colors, etc., are fixed conditions 

 as far as the individual is concerned, presumably brought about 

 by the age-long action of natural selection. But not a few 

 animals display the capability of achieving marked adaptive 

 changes, z. ., acquired variations, during their immature life 

 (post-embryonic development). It is obvious that insects of 

 complete metamorphosis, which possess in adult stage a color 

 scheme and pattern wholly different from that of the larva or 

 pupa and one which is not apparent until it appears in fixed 

 definitive condition on the emergence (and drying) of the 

 imago from the pupal cuticle, cannot be conceived to show, in 

 their color-pattern, variations due to individual adaptive changes. 

 That is, variations in this color-pattern among the individuals of a 

 species are not acquired (except in so far as they are produced by 

 the general influences of nutrition, temperature, etc., working 

 without reference to the external chromatic conditions of the en- 

 vironment) but are strictly congenital. 



Even such all-pervading influences as nutrition, temperature, 

 humidity and light may be, and in many cases obviously are, so 

 nearly practically identical for all the members of one brood or 

 even for all the individuals of the species, that they can have 

 little or no influence in causing variations. For conspicuous 

 example the case of the honeybee may be noted. Here all the 

 larvae live side by side under identical conditions (those of the 

 hive) of temperature, humidity and light, and the distribution of 

 exactly similar food to them in similar quantity is probably as 



