COLORS OF INSECTS. 12J 



tion, but are due to the influence of environmental conditions, food, moisture 

 and temperature, which have caused variation along a few lines and in no 

 others ; and it is in these lines that species are developed by the segregation of 

 units at points upon these lines of modification. This school holds the primi- 

 tive color pattern to be that of longitudinal stripes which break up into spots 

 and then fuse to form, first, transverse bands, and later a uniform color. New 

 markings appear upon the body from behind forward and from above down- 

 ward, or conversely, and old ones disappear in the same order and succes- 

 sion. Most of the data used in support of these views is drawn from the 

 study of adult coloration in Lepidoptera, wherein most of the bands and rows 

 of spots are transverse. But Eimer and his pupils boldly maintain that these 

 are longitudinal because parallel with the long axis of the body, and they 

 base their arguments for the validity of their doctrine thereon. With the 

 exception of von Linden, all of Eimer's followers base their conclusions upon 

 the study of adult color patterns, arranging these in series convenient for 

 their purposes. Yon Linden has studied the ontogeny of coloration in a 

 number of Lepidoptera, and claims that her results are in strong accord with 

 Eimer's views. However, an impartial examination of her observations and 

 figures fails to reveal any real confirmation of the theories so vigorously de- 

 fended. Likewise, the researches of Schaffer, von Bemmelen, Urech, Hasse, 

 and Mayer fail utterly to give support to the views of Eimer and his pupils. 



The researches of Piepers upon Pieridas and the larvae of Sphingidae and 

 my own studies upon several orders of insects show that there are definite 

 lines of color-pattern development (phylogenetically), which are inde- 

 pendent of environmental conditions and inherent in the animals them- 

 selves. Thus, in the Pieridse, Piepers shows that red, orange, yellow, and 

 white often follow in phylogenetic sequence, and black increases in amount 

 as this progressive change goes on. Mayer holds that the force of Piepers's 

 arguments is weakened by the fact that the colors of Pieridse are produced 

 by uric-acid derivatives, while those of other Lepidoptera are not. 



In my paper of 1903 I have shown that in several orders of insects there 

 are stages in development and many color-pattern features which are com- 

 mon to a wide range of insects, and that these are dependent upon physiolog- 

 ical activities in a very definite way and are in no wise related to environ- 

 ment. Thus, in the pronotum of various Coleoptera, it is shown that even in 

 distantly related families or in species living in diverse habitats there is a long 

 series of developmental stages in common ; and that it is only at the very end 

 of the series that specific and generic differences come in. In this instance 

 inherent structural and physiological characteristics are the controlling fac- 

 tors. Additional studies will undoubtedly verify and extend our knowledge 

 of the range of these phenomena. 



