ELEMENTARY SPECIES IN AGRICULTURE. 426 



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

 Without this precaution the rye of Schlanstedt would soon degene- 

 rate through accidental crosses with the local varieties." Such 

 crosses would, under any other conditions, be unavoidable and soon 

 wholly deteriorate the race ("Almanach du Cultivateur," 1892, p. 69). 



From this judgment, given by an authority who has so much 

 contributed to the wealth of northern France by the introduction of 

 this variety, we may deduce some conclusions as to the constancy of 

 Rimpau's rye. It is clear that Schribaux takes the race to be sub- 

 stantially 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 is in no need of any further improvement. 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, 

 therefore, for a large part remain hypothetical. If now we try to 

 give such an explication 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 obser- 

 ved or distinguished by him or by any other agriculturist of his time. 

 Among the ears which he selected a good number of these aberrant 

 types will, of course, have been represented, since he selected only 

 those which caught his eye by some striking useful difference from 

 the main type. Of course, he sought for ears of one and the same 

 ideal type, having a large number of big kernels. But notwith- 

 standing this, his handful of ears must have belonged to more than 

 one elementary species. Among these units of his selection some will 

 have been better yielders than others, and the subsequent selection 

 of his twenty years of pedigree-culture will slowly but surely have 

 eliminated the units of minor worth. This would result, at the end, 

 in a complete isolation of the best one of all the types, which he 

 originally, but unconsciously, selected and mixed. 



Or, in other words, Rimpau's pedigree culture was started as a 

 mixture of a number of excellent types, and his yearly selection 

 gradually reduced this number, until he had isolated and purified the 

 very best one among them. This point was, of course, only uncon- 



