2 BULLETIN 842, U. S. DEPARTMENT OF AGRICULTURE. 



sirable and timely to bring to general attention the data at hand, so 

 that the disease may be more readily recognized, its further importa- 

 tion and distribution prevented, and its control understood. 



HISTORY. 



Needham (24) / in 1743, in making microscopic examinations of 

 supposedly smutted grains of wheat, found that they contained nu- 

 merous motionless, eelworm larva? instead of spores. When placed 

 in water these larvae soon began eellike movements; hence, there is 

 this definite evidence of the occurrence of the disease in England at 

 this early date. At that time Needham briefly recorded his observa- 

 tions and again in 1745 (25) described the results of further investi- 

 gations, but was unaware of their full significance until Roffredi in 

 1775 (30) and 1776 (31) published the result of accurate investiga- 

 tions covering several years, which clearly showed for the first time 

 the causal relation of the nematodes to the malady and shed con- 

 siderable light on the life history of the parasite. In 1799, Steinbuch 

 (34) dealt with a disease of wild grass caused by a nematode which 

 he called Vibrio agrostidis and considered different from the wheat 

 eelworm. He appears to have been the first investigator who pro- 

 posed a name for the latter organism. He first refers to the parasite 

 in these words, " und welche Vibrio tritici genannt werden konnte," 

 and subsequently uses the name Vibrio tritici many times and in such 

 manner as to show conclusively that it is the wheat nematode of 

 which he is speaking. Bauer (3), in 1823, after considerable study 

 of and experimentation with the organism, also named it Vibrio 

 tritici, apparently unaware of the fact that it had been previously 

 thus designated by Steinbuch. Although Steinbuch was the first to 

 apply the binomial, Bauer seems to have been the first to use the name 

 systematically for the parasite. This doubtless accounts for the fact 

 that many later investigators cite him (Bauer) as authority for the 

 species. Dujardin (13), in 1845, transferred the species to the genus 

 Rhabditis. Ehabditis is a genus described by Dujardin and contains 

 mostly free-living forms which have little in common with Tylen- 

 chus. Diesing (12), an eminent systematic helminthologist, in 1850 

 also made a similar classification of the parasite. He placed it in the 

 genus Anguillula described by Hemprich and Ehrenberg. This 

 genus contains the vinegar eel and other free-living forms. Assum- 

 ing that the parasite occurred on other grasses than wheat, he ac- 

 cordingly called it Anguillula gramme arum. Diesing. In his classical 

 monograph, Bastian (2) in 1864, correctly transferred the old spe- 

 cies name as used by Steinbuch, i. e., tritici, to the genus Tylenchus. 



1 The numbers in parentheses refer to " Literature cited " at the end of this bulletin. 



