Novt='mber, 192; 



SCIENTIFIC AGRICULTURE 



83 



may in many cases display quite a cons- 

 picuous degree of uniformity in respect to 

 general appearance and growth, colour of 

 flowers and foliage, etc. Thus, Eriksson 

 (1, pp. 30-31) describes more or less in 

 detail nine local varieties from Sweden. 

 In most eases it is next to impossible to 

 express adequately the differences exist- 

 ing between the many local varieties. That 

 great differences exist between them, how- 

 ever, becomes evident when results of com- 

 parative tests are studied. Witte, who for 

 many years conducted variety tests with 

 red clover, states in this connection that 



there are grown in Sweden a great number 

 of red clover "varieties" differing from 

 each other in respect to yielding power, 

 growt^i after cutting, development, and 

 durability (3, p. 103). Under the circum- 

 stances, it is evident that different local 

 varieties may be of very different agri- 

 cultural value, a fact which, indeed, may 

 be of more importance to importers of 

 foreign seed than from what country the 

 seed is imported. 



Note.— The second part of this article deal- 

 ing with "Individual Variation and Inheritance 

 of Characters" will appear in the December 

 issue. 



The Genetic Basis for Improvement in Self- 

 Fertilized Crops 



By K. ALEX. BRINK. 

 Graduate Student, Bussey Institution, Harvard University. 



In tlie discussion of tliis subject the 

 writer has a two fold object in view, first, 

 to trace the development of genetic thought 

 as it hjs affected breeding practice with 

 autogamous plants and, secondly, to call 

 attention to a hitherto unemphasized pro- 

 perty of populations of pure lines. 

 I 

 To some it would seem superfluous to 

 argue the value of the contributions of 

 genetic science to crop improvement but 

 it is so frequently said that practice has 

 gained nothing by the discovery and eluci- 

 dation of the principles involved in heredity 

 that an examination of the facts will per- 

 haps serve a useful purpose. It is com- 

 monly contended and justly so, that the 

 majority of our most useful plants were 

 brought to their present degree of perfec- 

 tion before man knew of Mendelian in- 

 lieritance. It is equally true that the em- 

 jiirical means employed succeeded only at 

 the" cost of much vain hope and a vast 

 amount of fruitless effort. Success could 

 ensue only when the methods were in har- 

 mony with the underlying laws. Witli all 

 man's persistence and ingenuity prog ess 

 is but painfully made without clear think- 

 ing. And it is here that the revelations of 

 genetic science in late years have come to 

 his aid. A score of fallacies that have in- 

 fested the minds of animal breeders for 



centuries have fallen before the convincing 

 logic of controlled experiments, and the 

 modern plant breeder who has not made 

 genetics his best working tool is ill-equip- 

 ped, indeed. Perhaps no contribution of 

 genetic research has become more widely 

 incorporated in plant breeding projects 

 than the jnire line concept. It is todav the 

 basis of all intelligent efforts to improve 

 self-fertilized crops. Let us inquire into 

 the development of this idea. 



Since the first primitive attempts at 

 agriculture were made the best among dom- 

 estic animals and cultivated plants had 

 been chosen for propagation. Improve- 

 ment was in many cases, at least, unques- 

 tionably evident. Following the wide- 

 spread acceptance of the Darwinian theorv 

 of evolution advanced in 1859, it was be- 

 lieved that by the continual selection of in- 

 dividuals of a certain type, progress 

 would ensue in the direction of selection 

 Darwin's endorsement of the Lamarckiau 

 view that variations of all kinds were in- 

 herited seemed to explain in an adequate 

 manner the results that the breeders had' 

 obtained. Thirty-eight years after the 

 appearance of the famous "Origin of Spe- 

 cies" Sir Francis Galton elaborated the 

 law of ancestral inheritance. Galton it 

 was who introduced the statistical method 

 and applying it to tlie ])r.)blem of in- 



