164 



ON THE FLEECES OF CERTAIN PRIMITIVE 

 SPECIES OF SHEEPi 



By F. a. E. crew. 



{From the Animal Breeding Research Department, 

 The University, Edinburgh.) 



(With Plates I and II.) 



INTRODUCTION. 



At the present time extensive breeding experiments between Black- 

 faced ewes and Southdown rams are in progress with the ultimate object 

 of improving the fleece of the Scottish hill-sheep. To this end precise 

 knowledge of hair and of wool is necessary. 



In the fleece of the Southdown there is but one kind of fibre, recog- 

 nised as wool, while in that of the Blackfaced there are fibres very dis- 

 tinct one from the other and recognised as hair and wool respectively, 

 and also other fibres appearing to be of intermediate character, the 

 exact nature of which is not known. These indefinite fibres render the 

 above experiment extremely complicated yet full of interest to the 

 student of genetics. 



They may possibly be the common ancestral type of fibre from which 

 both hair and wool have sprung, or they may be but degenerate forms 

 of hair or wool or of both. 



An investigation of the characters, functions, and natural variability 

 of the fleece of the wild and primitive species of sheep, some of which are 

 known to have played a part in the production of the modern domesti- 

 cated breeds, may throw considerable light upon this problem of wool- 

 improvement and will provide standards to which the component fibres 

 of the modern fleeces may be referred. 



One of the distinguishing characters of mammals is the presence of 

 hair. Classed according to the nature of its growth, it is of two kinds: 

 temporary, being shed usually once a year and replaced by new hair, 

 and permanent, having a perennial growth. The summer coat is not shed, 

 it develops further to become the winter hair. The winter hair is shed in 

 the spring, the new summer coat replacing it. 



^ A grant in aid of publication has been received for this communication. 



