268 SOME RESCLTS OF OSTRICH INVESTIGATIONS. 



The aritlinietical means of five Fanners' Series are as 

 follows : — 



No. I, 25 birds 36.88 



No. 2, 24 birds 36.58 



No. 3, 19 birds 36.97 



No. 4, 50 birds 36 . 87 



No. 5. 19 birds 36.63 



Total mean 36 . 78 



The average number of plumes on the South African ostrich 

 is therefore the same as that on the North African, an important 

 conclusion which could not have been arrived at without the 

 opportunity of counting large numbers of each. 



As the northern ostriches now at Grootfontein were all 

 procured originally by the Arabs of Nigeria as chicks from wild 

 nests, and are uninfluenced by any artificial breeding, we may 

 presume that their plumes rei)resent the average for the North 

 African wild bird, and we have therefore good reason for con- 

 cluding that the ostriches over the whole continent of Africa 

 ])roduce the same average number of pliunes. From this it 

 follows that during the 50 years of ostrich farming in South 

 Africa no advance has been made on the average number of 

 plumes originally present on the wild bird. On the average 

 the domesticated birds of to-day produce the same quantity of 

 plumes as the original birds with which the first ostrich farmers 

 commenced in the sixties. 



Though somewhat remarkable at first sight, this result is 

 scarcely to be wondered at, if we bear in mind the principles 

 vmderlying ostrich breeding : Farmers have bred for quality; quan- 

 tity has never been taken into accou)it. Great advances have been 

 made in the so-called quality characters of the individual pliune,but 

 in doing this no attention has been given to the number of feathers 

 which one bird produces as compared with another, and therefore 

 no numerical change has taken place. It is a good instance of the 

 principle that no progress is ever made as a result of indiscrimi- 

 nate breeding, unless a character has some selection value or 

 mutations are taking place. 



Cross-bred Ostriches. — Seeing that the northern and southern 

 birds have the same average number of plumes and are a mixture 

 of heteri)zygotes, no change is to be expected in the number of 

 plumes on cross-bred chicks compared with what would be 

 procured by mating two northern or two southern birds. The table 

 given below is an example of the results which have been obtained. 

 The arithmetical mean of the parents is 36.24, and of the chicks 

 36.28, but for a larger series the average is 36.31, which agrees 

 more closely with that of the two races. A hint at factorial 

 purity is indicated, seeing that the extremes 33, 34, and 39 are not 

 represented. 



