CHAPTER Xlir 



CROSS-BREEDING EXPERIMENTS 



In July 1884 Beijerinck gave a lecture i) at the Netherlands 

 Agricultural Congress which must have drawn a good deal of atten- 

 tion. Using the work of earlier investigators as a basis — in particular 

 examples and experiments derived from Darwin's 'The Variation of 

 Animals and Plants iinder Domestication" — Beijerinck treated the 

 question as to whether varieties breeding true to type, with better 

 properties than the original varieties, may be produced by crossing of 

 species and of varieties of our cultivated plants, and by selection 

 among the descendants of these "mestizos" obtained by self-fertiliza- 

 tion or cross-f ertilization 2) . He argues f urther that among the high- 

 est-valued varieties of cultivated agricultural crops (at that time) 

 there may be pointed out a great number which originated from ac- 

 cidental cross-breeding, and that this number could be enlarged by 

 artificial and systematically performed cross-breeding experiments. 



He even concludes that the difficulty in improving the cultivated 

 plants is not so much to be found in the production of new varieties 

 as in the determination of their agricultural value. This leads him 

 to recommend that a Society be founded, for the purpose of not only 

 undertaking such cross-breeding experiments, but also of testing the 

 products in practice. 



Presumably, Beijerinck visualized a working scheme in which he 

 could join, since from those days dates the beginning of his cross- 

 breeding experiments with cereals which were carried out in Wage- 

 ningen, where he was aided by his colleague and friend Dr. P. Pitsch 

 and his pupil H. Dijt. Af ter Beijerinck moved to Delft, these ex- 

 periments (under his direction) were continued for some time by his 

 pupil. Only concerning the results of the cross-breeding of Triticum 

 species, are we f airly well enlightened ; on those with barley varieties 

 and barley species there appeared later, in 1888, a very short notice in 

 the publications of the Kon. Akademie van Wetenschappen 3) , from 

 which may be deduced that a continuation of these experiments 

 would probably have given important results. Apparently Beije- 



1) Kunnen onze cultuurplanten door kruising verbeterd worden ? Verslag van het 

 Landbouwcongres van 22-25 Juli 1884 te Amersfoort gehouden {Verzamelde Geschrif- 

 ten 1,359-366). 



2) Beijerinck recommends using the term mestizo for the just mentioned bastards, 

 and prefers to speak of "hybrids" and "hybridization" where nowadays the term 

 "cross-breeding of species" is used. 



3) Over kruisingsproeven met kultuurgerst, Versl. enMeded. Kon. Akad. v. Weten- 

 sch., Afd. Natuurk. Amsterdam 3de Reeks, 5, 202, 1888 [Verzamelde Geschriften 2, 189). 



