BLUE-GREEN CATERPILLARS 411 



17. That blueness of blood and hypodermis, whiteness of 

 cuticula, etc., are not due to a purely maternal blood variation 

 but to a typical recessive mutation, is evidenced by the large 

 numbers of blue-green caterpillars that appeared in two broods 

 of the original generation, both showing a typical 1 : 3 ratio, and by 

 the production in the next of both blue-green and grass-green 

 larvae by heterozygous [grass-green] parents and of blue-green 

 by homozygous [blue-green] parents. 



18. Normal grass-green caterpillars of G. philodice are pro- 

 tected by their color against the attacks of English sparrows. 

 From an outdoor culture exposed to sparrows for tw^elve days 

 the conspicuous blue-green caterpillars were practically all 

 eliminated, while many grass-green larvae were left unmolested 

 (as seen by comparison with two covered lots of the same brood) . 



19. The blue-green caterpillar is as vigorous and disease- 

 resistant as the normal, but the adults are less active and less 

 inclined to mate than their heterozygous, or normal homozygous, 

 brothers and sisters. 



20. A discussion of the relation of the blue-green blood pig- 

 ment to similar pigments in plants and animals, including a 

 mutation in blood pigment in the silkworm, concludes the paper. 



LITERATURE CITED 



Bird, J. E. 1903 Yellow colouring of cocoons of Plusia moneta; result of mois- 

 ture. The Entomologist, vol. 35, pp. 188, 242. 



Dubois, R. 1909 Recherches sur la pourpre et sur quelques autres pigments 

 animaux. Arch, de Zool. exper. et gen., 5e Ser., T. 2, pp. 471-590. 



Federley, H. 1920 Die Bedeutung der polymeren Factoren fiir die Zeichnung 

 der Lepidopteren. Hereditas, vol. 1, pp. 221-269. 



Fischer, E. 1901 Experimentelle Untersuchungen iiber die Vererbung erw^or- 

 bener Eigenschaften. Allg. Zeitsch. fur Entomologie, Bd. 6. 



Gerould, J. H. 1914 Species building by hybridization and mutation. Ameri- 

 can Naturalist, vol. 48, pp. 321-338. 



Geyer, K. 1913 Untersuchungen i'lber die chemische Zusammensetzung der 

 Insektenhamolymphe u. ihre Bedeutung fiir die geschlechtliche Dif- 

 ferenzierung. Zeitsch. wiss. Zool., Bd. 105, S. 349-499, Taf. 20-22. 



Haas, P., and Hill, T. G. 1917 An introduction to the chemistry of plant 

 products. London : Longmans, Green & Co. 



Harrison, J. W. H. 1920 Genetical studies in the moths of the geometrid 

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 in the Lepidoptera. Jour. Genetics, vol. 9, pp. 195-280. 



