THE ASSOCIATION OF CHARACTERS 277 



chapter, afforded the most promising instance, and was 

 studied first. Soon afterward other cereals and peas were 

 treated in the same manner, then vetches, but most of the 

 other agricuhural crops have been taken into consideration 

 only during the most recent years, or are still awaiting at- 

 tention. Gradually many hundreds of definite forms were 

 distinguished witliin each species, and the amount of work 

 became so large that it was necessary to divide the subject 

 among several investigators. Neither the time nor the 

 memory of one man was sufficient to embrace the whole 

 realm of the botanical marks and of their correlations to 

 breeding quahties for all the elementary forms of more 

 than one or two species. And perhaps just this statement 

 is the best way in which to convey to the layman an idea of 

 the enormous amount of work that is involved in this study, 

 and required for the complete exploration of all the single 

 forms, now growing mingled together in the fields. 



At Svalof the director Dr. Nilsson has chosen for his 

 own department, the cereals and especially the oats, and is 

 assisted in this work by Mr. Nilsson-Ehle. The leguminous 

 crops, such as peas and vetches, are the department of Dr. 

 Tedin. Rye has been studied by Mr. Wallden and potatoes 

 by Mr. Lundberg. Other special crops have been given 

 into the hands of Mr. Elofson and Mr. Witt. Each of 

 them has become a specialist in his line and has acquired 

 a high degree of abihty in singling out the rare promising 

 individuals from among the thousands of ordinary specimens, 

 which commonly constitute the majority of the ordinary 

 varieties. An instance of this v/ork was described in our 

 last chapter, in the production of a brewer's barley with 

 stiff culms. By such means it becomes possible to estimate 

 the probable agricultural value of all aberrant individuals. 

 Whenever a distinct quality is desired, either in order to 

 improve a local variety, or to bring it into a form suited for 



