516 A. H. STURTEVANT 
The white Wyandotte is a silver laced breed with a color pro- 
ducer dropped out. 
An attempt is made to explain three sets of phenomena, in fowls, 
in canaries, and in Aglia tau respectively, as cases of partial sex- 
linkage. Using this explanation, it is argued that the sex for- 
mula for birds and Lepidoptera is probably; 7, MM, FF; 9g, 
Mm, FF. The case of the dwarf guinea-pig is explained as per- 
haps representing partial sex-linkage in a form where the male 
is heterozygous for sex. 
February, 1912 ° 
LITERATURE CITED 
Bateson, W. 1902 Rep. Evol. Comm. vol. 1. 
1909 Mendel’s principles of heredity. Cambridge. 
BaTEson, W. AND PunneETT, R. C. 1905 Rep. Evol. Comm., vol. 2. 
1911 Jour. Genet., vol. 1, p. 185. 
CastTLE, W. E. 1903 The heredity of sex. Bull. Mus. Comp. Zool., Harvard, 
vol. 40, no. 4. 
Cook, M. H. 1910 Spermatogenesis in Lepidoptera. Proc. Acad. Nat. Sci., 
Philadelphia, April, p. 294. 
Correns, C. 1907 Die Bestimmung und Vererbung des Geschlechtes, nach 
neuen Versuchen mit hoéheren Pflanzen. Berlin. 
Davenport, C. B. 1906 Inheritance in poultry. Carnegie Inst. Washington 
Publ. 52. : 
1909 Inheritance of characteristics in domestic fowl. Carnegie Inst. 
Washington Publ. 121. 
1911 Another case of sex-limited heredity in poultry. Proc. Soe. 
Exp. Biol. Med., vol. 9, p. 19. 
DeperER, P. H. 1907 Spermatogenesis in Philosamia cynthia. Biol. Bull. 
ViOle el aren RmO A: 
DoncastER, L. 1908 Rep. Evol. Comm., 4 
1911 Some stages in the spermatogenesis of Abraxas grossulariata 
and its variety lacticolom Jour. Genet., vol. 1, p. 179. 
DoncastTER, L. AND Raynor, G. H. 1906 Breeding experiments with Lepid- 
optera. Proc. Zool. Soc., London, vol. 1, p. 125. 
