120 EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 



'blood' or hsemolymph of the pupa enters them; and soon after this, the wing 

 becomes of a uniform dull yellow or light drab color. This color is due to the 

 fact that soon after the hsemolymph has entered the scales, it changes to a dull 

 ochre-yellow and finally to a drab color. The same change takes place in hsemo- 

 lymph which has been removed from the pupa and exposed to the air. The 

 mature colors are clue to chemical changes in the hsemolymph itself. They 

 first appear in places between the nervures, never upon the nervures themselves. 

 The last places to acquire the mature coloration are the outer and costal edges 

 of the wings and the nervures. . . . 



''Dull ochre-yellow and drabs are, phylogenetically speaking, the oldest 

 pigmental colors in the Lepidoptera, for these are the colors that are assumed by 

 the haemolymph upon mere exposure to air. The more brilhant pigmental colors, 

 such as bright yellows, reds, greens, etc., are derived by more complex chemical 

 processes. We find that dull ochre-yellows and drabs are at the present day the 

 prevalent colors among the less differentiated nocturnal moths. The diurnal 

 forms of Lepidoptera have almost a monopoly of the brilhant colorations, but 

 even in these diurnal forms, one finds that duh yehow or drab colors are stih 

 quite common upon those parts of their wings that are hidden from view.'' 



The most recent researches upon the subject of development of color in 

 the pupal wings of Lepidoptera are those of von Linden ('98, '02). The results 

 of her investigations are embodied in two papers, the first being practically in- 

 cluded in the second. Her observations lead to the conclusion that the adult 

 color pattern develops from a number of separate transverse bands which dispose 

 themselves upon a uniform ground color in a manner characteristic of each 

 species. A distinction is thus made between ground color and that forming the 

 color pattern. These transverse bands (longitudinal according to Elmer's view) 

 occupy definite positions upon the wing determined by the course of the nervures 

 and trachese. This is the condition found among Papilios, Vanessas, Sphingids, 

 the higher Bombycids and even among some of the Geometrids. These larger 

 bands are formed by the broadening out and fusion of narrower bands ("bande- 

 lettes primaires") preserved only among more primitive forms. On the one 

 hand, the bands may fuse to form a uniform color; on the other, they may break 

 up into a series of spots, which become smaller as the ground color encroaches 

 upon them. The hindwing is arrested at a point less advanced than the fore- 

 wing; this, combined with the greater tendency toward fusion of the bands 

 which is in fact due to the modified form of the hindwing, creates the erroneous 

 impression that the hindwing is more advanced than the forewing. 



The author claims that her results support the laws which Eimer has promul- 

 gated for species differentiation based upon a study of adult coloration : 



"/Z est done evident que les his que Eimer a trouvees en etudiant la phylogenese 

 du dessin des Lepidopteres peuvent etre admises point pour point pour Vontogenese. 



"Mes reserches preuvent done que le dessin des Papihons ne parait pas 

 soudainement, . . . que les phases que ce dessin parcourt pendant son developpe- 



