U ,/.,, 



(I 



^^"Mmm^ 



TIIK PKODl CK OF A SI\(;i.K OLD SOKl . 



The four constant, "pure lines" of barley (Uordcuw distichum nutans) shown on 

 this and the opposite pagv, rejjresent cultures iscjlated from a trade variety 

 that has long been sold as homogeneous. A trial proved that a was in reality 

 composed ofa great number of difTerent "elementary species, each ot which, 

 when isolated and jiropagated bv itself, proved constant. 1 hese photographs 

 show four tvpes which difTer widely in habit. Taken by themselves, each 

 one can be 'used according to its in.lividual value; under the old system, 

 which existed universallv up to 20 years ago. and is .still in effect in many 

 countries, these four tvpes would have been planted mixed together as one, 

 and the cultivator would have had corresponding difliculty in profiting Irom 

 them. (Fig. 2.) 



284 



