122 CARNEGIE INSTITUTION OF WASHINGTON. 



than for any other breed. It has seemed very desirable to determine whether 

 similar laws hold for the other breeds of poultry. 



Studies of the White Wyandotte breed by Dr. Harris and of the Rhode 

 Island Red breed by Dr. Harris and Professor Goodale, of the Massachusetts 

 Agricultural Experiment Station, are now in press. While the numerical 

 values of the statistical constants differ somewhat from those found for the 

 White Leghorn, the results confirm in all essentials those already reported in 

 earlier Year Books and presented in detail in Genetics and other journals. 

 The possibilities of the prediction of the egg production of longer periods from 

 the recorded egg record of shorter periods is, therefore, not limited to one 

 peculiar breed, but is in all probability equally applicable to all the more 

 important commercial breeds. 



The foregoing studies have been limited to first-year production. Dr. 

 Harris and Professor Harry R. Lewis, of the New Jersey Agricultural Experi- 

 ment Station, have shown that similar correlations between the egg record of 

 various periods of the year obtain in the second laying year of the White 

 Leghorn fowl. Thus it should be possible to predict the second-year annual 

 production from the records of the individual months of the second laying 

 year, just as it has been shown to be possible to predict the annual production 

 of the first laying year from the records of individual months. 



A portion of the results of an investigation of the relationship between the 

 records of the individual months of the first year and the records of the 

 individual months of the second year are now in press, under the joint author- 

 ship of J. A. Harris and Harry R. Lewis. As pointed out in the last Year 

 Book, the results of these studies tend to throw considerable doubt upon the 

 importance of the so-called winter cycle as a distinct entity of importance in 

 the inheritance of fecundity in the fowl. These investigations are now show- 

 ing that there are definite laws underlying the distribution of the inter-mcnsual 

 corrcla lions of the first, of the second, and of the first and second years. These 

 will be ready for publication in the near future. 



In the course of the investigation of the relationship between the egg pro- 

 duction of the first and second years, it became evident that there must be a 

 fairly close correlation between the time of beginning and of cessation in the 

 first and second egg-laying years of the bird's life. A special investigation 

 was, therefore, made of this problem. The results of this study show that 

 there is not merely a correlation between the time of beginning of laying and 

 the time of cessation of laying in the first and second years respectively, but 

 that there is a definite correlation between the time of cessation of laying in 

 the first year and the beginning of laying in the second year. The results of 

 this study are now in press in Genetics. 



Differences in Rate of Growth of the Races of Mice. 



During the summer, Professor W. H. Gates, of the State University, Baton 

 Rouge, Louisiana, has been studying the rate of growth during the first three 

 weeks of young mice of the Japanese waltzing variety, of descendants of the 

 X-rayed non-waltzing and of control non-waltzing mice, with a view of 

 determining whether or not a racial difference in the rate of growth exists. 

 The data comprise observations made on about 1,000 animals. 



