SELECTION IN PURE LINES 



Many Experiments with Different Characters of Lentil, Vetch, Bean, Pea, Mustard 



and Oat Fail to Show Any Permanent Modification of Characters Pure 



Lines in Self-Fertile Plants Probably Unalterable by Selection 



PkoI-. Dk. C. I'^RlWIKTll 



Imperial School for Tcchnik, Menna, Austria 



PL' RE line is the name given by 

 johannsen to the self pollinated 

 descendants of a self pollinated 

 plant. The name "vegetative 

 line" was applied by me to designate 

 the descendants by vegetative propaga- 

 tion of a single plant' — what Webber 

 has called a clon.^ The word "line" 

 has also been used in various other ways, 

 and in genetic literature nowadays it is, 

 therefore, necessary to specify what one 

 means, when one employs this term. 

 In the present paper I shall use it 

 throughout in the sense given it !)>• 

 Johannsen. 



In a pure line of this sort, Johannsen 

 himself made the supposition that selec- 

 tion is powerless to change the heredi- 

 tary factors. His experiments with 

 beans and barley gave him the basis 

 for this supposition. 



During recent years his supposition 

 has been called in question in this 

 magazine, as for instance, by Belling' 

 and Castle, "^ while A. and C. Hagedoorn^ 

 have written in defense of it. 



Personally, I decided years ago, as 

 the result of various experiments of my 

 own, that Johannsen was correct in 

 saying that selection cannot alter the 

 character of a pure line. These experi- 

 ments were made with garden or 

 culinary peas (Pisum sativum) selection 

 being directed toward increasing or 

 decreasing the number of pods per 

 plant, and to increasing or decreasing 

 the per cent weight of peas as compared 

 with the weight of the whole plant." 



Lately I concluded a series of 

 experiments on the same subject, with 

 a view also to determining the frequency 

 of spontaneous variations (mutations). 

 Concerning the effect of selection, the 

 following kinds of characters were 

 examined : 



1 . External characters, showing quali- 

 tative variations (in snap beans and 

 white mustard) or small quantitative 

 variations (in peas and lentils) ; 



2. External characters showing very 

 large quantitative variations (in oats); 



3. Internal characters showing very 

 large quantitative variations (in oats). 



1. The ])ure lines studied under the 

 first head have all been bagged before 

 flowering, in every generation, and were 

 therefore self-pollinated. The pure-line 

 selections (which alone are considered 

 in this paper) were preceded in each 

 case by mass selection in the same 

 direction, and all the plants used to 

 continue the line were protected against 

 cross-fertilization . 



RESULTS OF TRIALS 



The results of these trials may be 

 summed up as follows: 



(a) In eight generations of selection 

 with a lentil {Lens esculenta) called the 

 Krain lentil, which has seeds in part 

 solid brown in color and the rest t)lack 

 s])()tted — both kinds of seeds appearing 

 also on the same i)lanl ; / failed to bring 

 the l)lack spots to full heredity, or even 

 intensify their heredity; and on the 

 other hand selection of jilants with no 



' Fruwirth: Die Ziichtung landw. Kulturpflanzen. I, 4th ed., p. 14. 



* Science (New Yr)rk), 1913, p. 501. 



* American Breeders' Magazine, III, p. .^11. 



* THK JOIRNAL OK IIlLREniTY, V, p. 9.S. 



^American Breeders' Maf^azin<\ I\\ j). 165. 



"Fruwirth: UntersiuhunRen uber den ICrfolg u. die zweckmissigste Art der Dur hfuhrung 

 von Vcredlungsauslcse \>v\ Pllanzen von Sclbstbefnichtern. Archiv Cesellscltaf(, Berlin, 1907. 



90 



