BLUE-GREEN CATERPILLARS 393 



could decolorize the relatively large mass of yolk-filled protoplasm 

 presumably at the time cream-colored, and make it appear like 

 the egg of a homozygous female pure white. 



Moreover, Toyama ('13) has shown that in the silkworm not 

 only the color of the newly laid egg, but even the color of the 

 serosa (containing nuclei that combine both paternal and mater- 

 nal genes) show only maternal inheritance. The action of the 

 paternal gene is entirely neutralized or masked in reciprocal 

 crosses by some maternal effect, which, in the opinion of the 

 present writer, must lie in the composition and action of the 

 maternal blood. 



BLOOD AND BODY COLOR OF THE LARVA 



The mutation is not evident during the first stage of larval 

 development, when the skin is relatively opaque, nor until the 

 end of the second. At that time, just before the second molt 

 when the skin is tightly stretched, the young larva becomes 

 distinctly bluish, and after the second molt conspicuously 

 and even brilliantly blue-green. 



Full-grown caterpillars (pi. 1, fig. 1) correspond in color to 'light 

 porcelain green' (Ridgeway, '12, pi. 33, B-G) above and 'Niagara 

 green' below, running into 'Montpelier green' on the head, which 

 is shghtly darker. I am indebted to Prof. A. Ames, an artist and 

 authority in optics, for assistance in this determination. Another 

 mature caterpillar was a shade darker, 'Montpelier green.' 



A distinctive feature of the blue-green caterpillar is the entire 

 absence of the pink line that in a normal larva is traced more 

 or less plainly along the middle of the lateral white band running 

 through the stigmata. The pink lateral line of the normal, 

 larva is, therefore, a dominant character completely correlated 

 with grass-green hemolymph. 



COLOR OF THE PUPA AND OF ITS CUTICULA 



The pupa (fig, 2) is somewhat less blue than the larva, but its 

 hypodermal color is a well-marked discontinuous variation from 

 the normal grass-green hue (fig. 2a). Its ground color corre- 

 sponds to a blue-green called 'Rejane green' by Ridgeway ('12, 

 pi. 33, GB-G.) 



