248 SOME RESULTS OF OSTRICH INVESTIGATIONS. 



It is no small achievement for the South African farmer to 

 have, within 50 years, reduced the. wild, highly nervous, ostrich 

 to a thorough state of domestication, to have worked out the 

 details of management necessary for the production of successive 

 plumage crops of the highest perfection, to have combated the 

 many parasitic diseases to which the bird is" subject, to have 

 elaborated methods of breeding and chick-rearing, and, by 

 selection, to have advanced the plume to the high state 

 of excellence in which it is now found. 



A fact most impressive to the physiologist is the unusually 

 sensitive nature of the feather growth. Unless the bird is main- 

 tained in the highest nutritive condition throughout the six nronths 

 required for a feather crop to grow and mature, the character and 

 quality of the plumage suffer; and any imj)erfection of growth 

 greatly depreciates the ])lume in value. The feather is an epi- 

 dermal product, nourished from a long dermal medulla, and like 

 all epidermal structures — hairs, nails, hoofs, and horns — is deli- 

 cately responsive to nutritive variations and changes in external 

 conditions. Even the normal variations in blood-pressure between 

 the night and day ]:)eriods often leave their mark upon the 

 growing ])lume, in the form of night and day rings. These 

 represent alternating differences in density in the new feather 

 growth, and are the foundation of the prevalent defects techm"cally 

 known as " bars," the nature of which has been investigated for 

 several years by the writer.* (PI. 3A.) The longest ])lumes have a 

 growth at the rate of a quarter of an inch a day, and all the 

 feathers are so many projecting cylinders, full of blood capillaries, 

 closed at the outer end and open below to the blood sup]jly. To 

 maintain the uniform blood-pressure necessary for the growing 

 feather to attciin its highest perfection demands a constant supply 

 of highly nom-ishing food, such as lucerne, rape, mangel, and all 

 l<inds of grain. It can safely be said that no animal is so highly 

 cared- for. and leads such a pampered existence, as the high-grade 

 domesticated ostrich. The farmer, however, has no option in the 

 matter. The difference in returns from a perfectly grown feather 

 crop of high quality and one defective in growth is often the 

 difference between prosperity and failure. 



The method of securing a full, complete, and even feather 

 crop is a matter of some interest to the zoologist. In North Africa 

 the entire i)lumage is usually plucked from body, wings, and tail, 

 a measure which leads to rapid deterioration in the successive 

 crops ; but in methodical ostrich-farming, only the three main 

 rows of wing feathers are taken (PI. 412), along with the tail. 

 With care, the same character of plumage may be procured year 

 after year, maybe for 50 or more years. In farming, the object 

 is to maintain all the commercial feathers at the same stage of 

 growth at the same time ; in other words, to keep the crop even. 

 The natunil method does not suffice, for the moulting of the 



* " Experiments with Ostriches, X : How the Bars in Ostridi Feathers 

 ;iri- prdduccfl." C.C.U. Agric. Jctini-. Oct., 19OQ. 



