HISTORY AND BIBLIOGRAPHY 827 



and Clark of the Dominion of Canada and in numerous notices in 

 the agricultural press of the northern United States. 



Broom rape has been discussed by Garman of Kentucky and by 

 the United States Department of Agriculture. 



Much has been published on the subject of weed seeds. The 

 more important contributions are the following:* 



European work. — The importance of this work has long been 

 recognized in Europe. The pioneer work in this line was carried 

 on first in Germany, a station for testing commercial seeds having 

 been organized in 1867 in connection with an academy located in 

 Tharandt. Dr. Nobbe was its first director. Early in his work 

 he saw the importance of making careful examination for the im- 

 purities of various grass and clover seeds. In 1876 appeared his 

 classical book, Handbuch der Samenkunde. In addition to this 

 work he was the author of many other important papers on via- 

 bility of seeds and other physiological seed problems. 



Among other important contributions along this line, we may 

 mention the papers and work of Kraft, Luhn, and Harz. The work 

 of Harz summarizes not only the facts pertaining to the anatomy 

 of seeds but also to many other important topics; the literature 

 bearing on the subject of seeds is also given. 



The work of Burchard on the adulteration of seed with special 

 reference to their origin is particularly noteworthy. In his book 

 he has published statistical records showing the origin of clover 

 seed and the weed seeds found in the same from Middle Europe, 

 Eastern Europe, Southern Europe and North and South America. 

 He sometimes missed the important weed species that are found 

 in our American clover seed, but on the whole it is true that the 

 character of the weed seeds found in our clover and other seeds 

 will enable one to tell where they were grown. 



Burchard, in his account published in a contribution from the 

 Seed Control Station of Hamburg, states that a large number of 

 seeds investigated by him had impurities. Of two hundred and 

 eighty seeds tested, one hundred and sixty-seven belonged to the 

 pulse family, seventy-nine to the grass family, twenty-three to 

 forest seeds, and eleven were miscellaneous. He found the mini- 

 mum purity of the clover seed was 54.2 per cent. The highest 

 percentage of purity was found in timothy, 99.42. The lowest 

 germinative energy was found in fescue grass, 0.17 per cent, and 



*The more important references here given upon the history of seed investi- 

 gation are taken from bulletins 88, 99 and 105, issued by the Iowa State Agri- 

 cultural Experiment Station, which are more completely listed in the bibliography. 



