J. K. DUERDRN \(^\ 



Among the many wild HtminH; but it hiis hwu found iiniHiHsiblc to 

 choiigv liny «»f tluM'hiinioUTistics hrymul wluitniitiin* providrd. Tiiking 

 the fentun'M 8o|Ninitidy th** ostrich pliiinc atVonls a noteworthy inHUmcc 

 of the ini{M>ssihiIity of iniproveimnt. heyoinl thr maxima originally 

 pri'MMit, by meuiui of continued s«'l<'et.ivr bn-eding. All thjit tlu* pnK-rKs 

 haH achiev(sl is t-o s<'gn'gate the ehanicU^rs niost desired; moreovir, in 

 connei'tion with the |>oints of the feather no hint of any sj)ort or muta- 

 tion ever <H*eurs. 



When t»om|)aring closely the many connnercial varietit's of ostrich 

 phnnes, ench repivsenting a separat** tyjK? to the specialist and having 

 a distinct value, the (juestion arises as to how far th(» many differences 

 in size, density, shajH' and lustre should be considered as Huctuating 

 variations, or how far they are eJementjiry chanicters. Farming ex[K'ri- 

 ence has fully proved that selective breeding within a typo will not 

 change any of the minutiae of the type. If a farmer requires any 

 particular featuiv juJded to his strain he must procure it from birds 

 whose plumage displays it: no <legree of breeding will otherwise produce 

 it. It is thus shown that the variations distinguishing the types are 

 germinal, not environmental, and should therefore be reganted as repre- 

 senting definite elementary characters. Yet how many of these elementary 

 characters must be represented in even a single ostrich plume! No 

 doubt the same multiplicity of small characters appeals to the specialist 

 in an intensive study of any domesticated stock. Experimental investi- 

 gations are usually undertaken on one or on only a few of the pronounced 

 characters, but when all the many details have to be considert^d which 

 are of the greatest importance to the practical breeder, there appears 

 no limit to w'hich analysis can be carried'. 



The present paper is confined to the behaviour in crosses of certiiin 

 of the more prominent characters which distinguish the northern and 

 southern ostrich, such jis the dimensions, colour, the bald head patch 

 and details connected with the egg, and others which the two have in 

 common, such as the number of plumes on the wing, the scales on the 

 middle toe and the claw on the fourth toe. An attempt is made to 

 arrive at the germinal constitution of the ostrich so far as concerns these 

 characters, as well as their adaptive value and manner of establishment 

 in the race. 



' Two preliminary attempts have already been made to analyse the various plume 

 characters of the parents and progeny in cross-matings, Breedimi ExpcrimcntK ivith North 

 African and South African Ostriches, I. "The Plumes of Parents and Chicks " ; II, "The 

 Flames of the Second and Third Clippings," Local Series, Nos. 13 and 17, Department of 

 Agriculture, Union of South Africa, 1917. 



