246 ROMMEL AND PHILLIPS— INHERITANCE IN [October 19 



of offspring born at one time, is a most valuable point, both from 

 the standpoint of practical breeding and from that of theoretical 

 consideration. Up to the present time, statistics on the inheritance 

 of number of offspring in mammals is represented only by the work 

 of Pearson, Lee, and Bramley-Moore (1899),^ on man and thorough- 

 bred race horses. In this work, it was found that fertility (total 

 number of oft'spring) is inherited. By limiting the duration of 

 marriage to fifteen years or more, the correlation of fertility in man 

 was found to be larger than when no such limitation was made, a 

 result which is in itself obvious. In the work on thoroughbred race 

 horses the same method was employed making limitations according 

 to number of coverings. In the work reported in this paper the 

 total number of offspring born at one time is the only problem 

 considered, and the length of the breeding period of parents does 

 not effect the results except in the way shown, that the correlation 

 decreases with the age of the sow. 



In a recent paper by Castle and others (1906), this problem is 

 taken up in Drosophila ampelopJiilo, Low. The results of this work 

 show that there is " an unmistakable tendency for the larger parental 

 brood to produce larger filial broods, but not so much larger as the 

 difference in the parental brood would lead us to expect." 



The method of work for the original problem is described by 

 Rommel (1906) as follows: 



" The Poland China records generally publish the registration of hogs accord- 

 ing to the following plan or modifications of it : 



Magnet's Model 2d, 135786. 



Farrowed March 28, 1902. Litter, 7; raised — boars, o; sows, 4. 



Black with white points. 



Bred and owned by W. C. Williams and Gardner, Bryant, Jay County, Ind. 



Sire : Tecumseh Magnet, 46925 ; he by Nelson's Magnet, 35535, and out of 



Miss Rosa, 75542. 

 Dam: Gardner's Model, 122578, by Invincible Chief, ^^^^JJ, etc. 



" This is the registration of a sow on page 282 of volume 26 of the ' Ohio 

 Poland China Record.' 



"For each hog registered a card (size about 2 by 4% inches) was written 

 according to the following plan : 

 Name and number of dam. 



^Mathematical Contributions, etc., VI, " Genetic (Reproductive) Selec- 

 tion : Inheritance of Fertility in Man, and of Fecundity in Thoroughbred 

 Race Horses," Phil. Trans.. A, CXCII, 257-330. 



