320 



THE AMEBIC AN NATURALIST [Vol. LII 



19. The relation between the means of the abstract 

 numbers, in the series 1-30 and 30 to some higher num- 

 ber, and its bearing on the use of the means of egg pro- 

 duction of two groups falling within the same limits is 

 discussed. 



20. The curves of winter egg production are shown to 

 be compound curves. 



21. A knowledge of the factors described is of im- 

 portance both from the commercial and biological stand- 

 points. As Pearl and Surface ( '08) pointed out a number 

 of years ago, the income received from each bird will 

 depend not only on the number of eggs produced, but also 

 on the season at which those eggs are laid. A bird that 

 produces 100 eggs at suitable seasons may yield as much 

 income as a bird that produces 200 eggs at less profitable 

 seasons. 



From the biological standpoint, a knowledge of the 

 separate factors is important because what might seem at 

 first sight to be a simple character is really extremely 

 complex. Obviously, then, it is necessary to attack the 

 problem from this standpoint. 



LITERATURE CITED 



Castle, W. E. 



1915. Some Experiments in Mass Selection. Am. Nat., Vol. XLIX. 



1916. Can Selection Cause Genetic Change? Am. Nat., Vol. XLX. 

 Curtis, M. R. 



1914. A Biomedical Study, etc. IV. Factors Influencing the Size, 

 Shape, and Physical Constitution of Eggs. Arch, Ent. Org., 

 Bd. XXXIX. 



Dryden, J. 



1916. Poultry Breeding and Management. Springfield. 

 Goodale, H. D. 



1918. Winter Cycle of Egg Production in the Rhode Island Red 

 Breed of Domestic Fowl. Journ. Agri. Eesearch, Vol. XII. 

 Gowell, G. M. 



1902. Breeding for Egg Production. Maine Agri. Exp. Sta. Bui. 79. 



1903. Breeding for Egg Production. The same, Bui. 93. 



1905. Poultry Experiments. The same, Bui. 117. 



1906. Poultry Experiments. The same, Bui. 130. 



