3l8 R. M. STRONG. 



most all of the blond birds are males. Male white birds appear, 

 however, when white hybrid females are crossed back on white 

 stock males. 



3. The nestling hybrids are identical in appearance with the 

 nestlings of the corresponding blond and white uncrossed ring- 

 doves. 



4. The phenomena observed are remarkably similar to those 

 described by Durham and Marryat ('08) for canaries. 



5. Sex-linked inheritance in birds and elsewhere also can be 

 explained, in my judgment, more logically with the assump- 

 tion that the male is heterozygous for sex and the female 

 homozygous, than by the contrary hypothesis. 



6. The appearance of recessive characters in FI when the male 

 parent is recessive may be explained with the assumption that 

 the female determining gametes of the male parent may either 

 possess or lack something which is responsible for the absence in 

 female offspring of dominant characters carried by the female 

 parent. 



7. No evidence was obtained in support of the old idea that 

 the first egg laid by doves produces a male. 



8. Observations concerning the period of incubation and other 

 points in the breeding habits of ring-doves are described. 



LITERATURE CITED. 

 Bateson, W. 



'09 Mendel's Principles of Heredity. University Press. Cambridge, England, 



396 pp. 

 Cole, L. J. 



'n Sex Ratio and other Reproduction Statistics in Tumbler Pigeons. Science, 



n. s., Vol. 33, No. 842, p. 270. 

 Craig, W. 



'08 The Voices of Pigeons Regarded as a Means of Social Control. Am. Jr 



Sociology, Vol. XIV., No. i, July, pp. 86-100. 



'09 The Expressions of Emotion in the Pigeons. I. The Blond Ring-dove 

 (Turtur risorius). Jr. Comp. Neur. and Psychol., Vol. XIX., No. i, April, 

 pp. 29-80, i plate. 

 Davenport, C. B. 



'n Another Case of Sex-limited Heredity in Poultry. Proc. Soc. for Exper. 



Biol. and Med., Vol. 9, pp. 19-20. 

 '12 Sex-limited Inheritance in Poultry. Jr. Exper. Zool., Vol. 13, No. I, July, 



pp. 1-26. Eight colored plates. 

 Doncaster, L., and Raynor, G. H. 



'06 On Breeding Experiments with Lepidoptera. Proc. Zool. Soc. London, Vol. 

 i, pp. 125-133, PI. VIII. 



