128 CARNEGIE INSTITUTION OF V/ASHINGTON. 



HEREDITY OF ATAXIA AND DEFECTIVE PLUMAGE IN PIGEONS. 



These two defects have been studied together in the same stock of 

 common pigeons by Dr. Riddle, and the fom'th generation has now- 

 been obtained. The ataxia arose in a single individual, a female. The 

 defective plumage ("scraggliness") has rarely appeared in our stock. 

 It has been bred from the only adult living bird (a male) of this kind 

 which we possessed. The fact is to be noted here that both these 

 rarely occurring defects have been perpetuated quite undiminished to 

 the fourth generation. 



HEREDITY IN MAN. 



Stature.— The Director, in cooperation with the Eugenics Record 

 Office, has completed a study of inheritance of human stature, which 

 has been pubUshed in Genetics. »Stature has long been a classical 

 object of investigation, largely because it is so readily measured. Thus, 

 in 1889 Galton pubhshed his studies on stature in parents and children 

 and their interrelation. This led to Professor Karl Pearson's remarka- 

 ble series of investigations "Mathematical Contributions to the Theory 

 of Evolution" that founded the biometric school, which has left its 

 imprint on biology, though it has proved disappointing in its assist- 

 ance to the study of heredity. Though stature is the end-result of a 

 number of independently varying elements, still, because of facts that 

 determine growth as a whole, and because the length of the separate 

 segments of stature are separately inheritable, it is possible to find some 

 law of inheritance of the trait. 



The present study was made on data derived from 3,298 children, 

 their 1,738 parents, and a number of grandparents, uncles, and aunts. 

 A large proportion of these were especially measured at their homes in 

 various parts of the country. The hypothesis is supported that 

 while short parents tend, on the average, to have short children, they 

 may, and frequently do, carry germ-cells which lack the shortening 

 factors; on the other hand, all of the children of tall parents are tall. 

 Consequently the offspring of two very short or short parents are more 

 variable in stature than the offspring of two very tall or tall parents 

 as 2.4 is to 2.2. Also, whereas the offspring of two very short or short 

 parents tend, on the average, to be less extreme than the parents, this 

 is not tnie of the offspring of two very tall or tall parents. 



Not only is stature as a whole inherited, but also, and even more 

 clearly, each segment of stature, such as neck, length of torso, thigh, 

 and foreleg; and the inheritance of the length of these segments follows 

 the same law as does stature as a whole. An interesting by-product of 

 this study is that persons of similar stature tend to marry each other, 

 and the more extreme their stature the more particular are persons in 

 this respect. Among 869 matings that of a very short man to a very 



