288 GENETICS IN RELATION TO AGRICULTURE 



1768 nearly 2000 sorts were known in Holland. But in 1864 only 700 

 varieties were found in the largest garden in Haarlem, which fact in- 

 dicates a gradual process of elimination of the less desirable selections 

 of earlier years. 



Pioneers in Plant Breeding. The systematic breeding of crop plants 

 was begun in Europe during the latter part of the 18th century. Jean 

 Baptiste Van Mons, a Belgian physician and professor of physics and 

 chemistry in the University of Louvain, pursued plant breeding work as 

 an avocation. But so great was his zeal in an effort to demonstrate 

 certain theoretical ideas which he held concerning the improvement 

 of fruits that the results of his labor were extensive. His experiments 

 were begun in 1785. Thirty-eight years later he had 80,000 seedling 

 trees in his "Nursery of Fidelity," as he called it, at Louvain. He dis- 

 tributed cions without charge to many countries including America. 

 He specialized on pears and his first catalogue, issued in 1823, lists 

 1050 varieties. Altogether he originated nearly half -that number. 

 Van Mons' service to agriculture, especially to pomology, has been 

 widely recognized. 1 



Three other pioneer breeders who began their work during Van 

 Mons' life are Thaer, Knight, and Cooper, representing Germany, Eng- 

 land, and the United States respectively. During the latter portion of 

 the 18th and the earlier years of the 19th centuries each of thege men 

 carried on experiments in plant breeding and made contributions of 

 tremendous importance to agriculture. Thomas Andrew Knight was the 

 first to show the value of hybridization in plant improvement. Accord- 

 ing to Bailey, in the variety, accuracy, significance, and candor of his 

 experiments, Knight stands to the present day without a rival among 

 horticulturists. He was also a successful breeder of livestock and author 

 of papers on plant physiology and breeding. Albrecht Daniel Thaer 

 also made hybridizing experiments but emphasized the value of selection. 

 Plant breeding was only one of his many agricultural interests and he is 

 credited with having laid the foundation of scientific agriculture of 

 today. Joseph Cooper disproved the current fallacy as to the entire 

 necessity for changing seed and showed the American farmer the impor- 

 tance " of selecting seeds and roots for planting or sowing, from such vege- 

 tables as come to the greatest perfection, in the soil which he cultivates." 

 Like Van Mons, each of these men had his theories, but only experience 

 revealed the truth in those theories. Based on their experience they 

 formulated certain rules which they knew would yield results, but fre- 

 quently the conclusions reached by them were only partially true. 



At least five other men deserve to be mentioned among the earlier 



1 For a discussion of Van Mons' theories and contributions (also of the work of 

 Knight and Cooper) see BAILEY, L. H.: "Survival of the Unlike," 1906, pp. 141-159. 



