98 PLANT-BREEDING 



Institut Agronomique of Paris explains the conditions of 

 keeping the Schlanstedt rye up to its original qualities. He 

 says: "In order to do this, care must be taken to sow the 

 seeds on a field which is as far removed as possible from all 

 other cultures of rye. Moreover, the field should be large 

 and protected all around by a hedge of trees and shrubs. 

 Without this precaution the rye of Schlanstedt would soon 

 degenerate through accidental crosses with the local varieties." 

 Such crosses would under any other conditions be unavoid- 

 able and soon wholly deteriorate the race (Almanach du 

 Cultivateur 1892, p. 69). 



From this judgment, given by an authority who has so 

 greatly contributed to the wealth of northern France by 

 the introduction of this variety, we may deduce some con- 

 clusions as to the constancy of Rimpau's rye. It is clear 

 that Schribaux takes the race to be substantially constant 

 and explains the necessity of continued selection only by 

 the impending danger of crosses with varieties of minor 

 value. Hence it follows that the main significance of the 

 pedigree- culture on the farm of Rimpau must be the same, 

 and that at least in later years his pedigree must have gained 

 a degree of uniformity, which was in no need of any further 

 improvements. The real act of effective selection is thereby 

 brought back to the first years, but how many generations 

 of true selection it has taken to render the rye of Schlanstedt 

 uniform and pure, it will of course always remain impossible 

 to tell. The explanation of Rimpau's success must there- 

 fore remain largely hypothetical. If now we try to give 

 such an explanation on the ground of the theory of mutation 

 and of the already quoted discoveries of Nilsson we may 

 suggest the following: At the period when Rimpau started 

 his pedigree, his rye fields must have contained numerous 

 elementary species, not observed or distinguished by him 

 or by any other agriculturist of his time. Among the ears 



