DIFFERENTIATION OF GRAFTED WING-GERMS 471 



do with male wings developed on female organisms. The grafted 

 wings were somewhat folded and could not be drawn out of the 

 pupal integument by the moth alone. During the extraction of 

 these wings the scales, especially from the upper surface, nearly 

 all remained in the pupal skin, from which they could very 

 easily be removed uninjured. The form and color of the scales 

 were afterward studied exactly under the microscope. 



In one case the form of these scales was quite normal, in the 

 other the scales were less deeply dentated than in normal con- 

 ditions, which seemed to show that they were not completely 

 developed. The color of these wings corresponds to the dimor- 

 phic hue which the transplanted wing would have had if it had 

 remained intact in the previous organism; therefore, the grafted 

 wing was in both cases otherwise colored than the normal left 

 wing of its foster-mother. The wings of the male, which had 

 been transplanted on the female, had more or less dark gray or 

 dark brown scales, in contrast to the female wings, which were 

 for the most part white. 



I think the results of these experiments certainly speak in 

 favor of Mayer's theory, as it turned out that the cells of the 

 wing germs were able to collect the respective dimorphic pig- 

 ments in their scales, forming them from the heterogeneous blood 

 of the other sex in the new surroundings. Thus the pigments of 

 the scales are not directly derived from the desiccation of the 

 haemolymph, but must be the outcome of certain chemical proc- 

 esses occurring in the insect blood under the influence of sub- 

 stances formed in the scale-producing cells, and considered by 

 Mayer to be ferments. Owing to these substances, which are 

 different in different parts of the imaginal wing, various pig- 

 ments are formed in the blood of the insect, and this results in the 

 production of complicated figures on the wings. These substances 

 develop by means of physiological self-differentiation, and their 

 formation is outside the influence of the haemolymph of the 

 other sex. This fact is unexpected, since the investigations 

 made by Dewitz ('09-'16b), Steche ('12 a, b,) and Geyer 

 ('13, '14) have demonstrated that the blood in insects of one and 

 the other sex is not the same, but shows great differences in the 



