PHYSICAL CHARACTERS IN MAN 109 



through three generations (four individuals) in a 

 Swedish peasant family. The condition is probably 

 similar to paralysis agitans, which is said to be due 

 to the degeneration of the parathyroid gland. 



Ataxia in pigeons is apparently a very similar 

 condition. In 1914 Riddle (191 8) obtained in 

 breeding experiments a female pigeon with marked 

 lack of control over the voluntary movements of 

 head and body. It appeared, probably as a muta- 

 tion, under conditions of " reproductive overwork," 

 in which the bird is obliged to continue laying by 

 removing the eggs; and the condition has been in- 

 herited through five generations. About 175 young 

 have been reared, and of this number 1 19 were classi- 

 fied as normal and 46 as affected. From these and 

 other matings the evidence indicates that ataxia is 

 inherited as a simple recessive with some irregularities. 

 Affected birds show quivering movements, nodding 

 heads, unsteady gait, and irregular flight in various 

 degrees. Koch and Riddle (191 8) analysed the 

 brains of ataxic birds in comparison with the normal. 

 They found in the former higher values for water 

 content, protein, and extractive sulphur, with lower 

 values for lipoids, phosphatids, and cholesterol. 

 The results suggest a chemical immaturity or under- 

 development of the affected brain, more like those 

 of normals at a younger stage of development, but 

 further investigations of this subject are desirable. 



In the mountains of Georgia a family is found 

 (vStuckey, 191 6) some of whose members for four 

 generations have had constricted eyelids. The sight 

 is normal, yet owing to this constriction it is necessary 

 for them to avert their heads in order to see. The 

 manner of inheritance indicates a segregating domi- 

 nant character. 



Another peculiar case, of hereditary nose bleed, 

 is recorded (Lane, 191 6), members of a famil}' in 



