A STUDY OF FUNDAMENTAL BARS IN FEATHERS. 169 



reported the abnormality in the ostriches, particularly in those 

 of South Africa. I learn from him by letter that he has under- 

 taken a thoroughgoing research to determine the cause of the 

 " barring " so prevalent in the ostriches. He estimates that the 

 value of the ostrich plumes from South Africa alone are from 

 this cause depreciated in value to the extent of ,250,000 

 annually. 



The defects are, however, not confined to hybrid pigeons and 

 domesticated ostriches. I find them in the most widely separated 

 bird groups ; in primitive and in recent birds ; in land and in 

 water birds ; in domesticated and in wild birds ; in birds from the 

 arctic and from the torrid zone, etc. I have been able, owing to 

 the courtesies extended by Professor C. B. Cory and Dr. Ned 

 Dearborn, of the Field Columbian Museum in Chicago, to exam- 

 ine a very great variety of birds belonging to the Museum. I 

 find that although it is not easy to see evident defects in every 

 specimen, it is easy to find them in every species. We may con- 

 clude therefore, that they are to be found in all birds. 



It is a fact, and a significant one I think, that the defects are, 

 in general, more common in domesticated and caged birds than 

 in wild birds. In this connection, however, it should be stated 

 that the defects appear indifferently in pure breeds, hybrids and 

 mongrels. At any rate I have verified this in a number of 

 our domesticated birds. 



On Individual Birds. --\ have found the defects in all of the 

 plumages of the birds, with the possible exception of the first 

 or downy plumage. In some birds the defects seem to occur 

 more frequently in the juvenal (of D wight) than in the others. 

 The emphasized defects appear in all the feather-tracts or pter- 

 ylae ; but in a particular bird, and usually in a particular species, 

 certain tracts show them in greater numbers than do others. 



/// an Individual Feather. In the feather there may be pro- 

 duced at any point in its length, either of the five types of ab- 

 normality. In some birds (Callus] the distal part of the feather 

 oftener shows the defective areas ; the proximal end, the deep 

 constrictions, while we get defective lines in one form or another 

 at every point in the feather's length. 



