202 AGRICULTURAL EXPERIMENT STATION. [Jan. 



view in a popular form, although the knots and the accom- 

 panying fungus had already been described by the pioneer 

 student of American fungi, de Schweinitz, who appears 

 to have regarded the knots as the combined result of the 

 attacks of a gall fly and the fungus, to which he gave the 

 name Sphceria morbosa.* In 1831 he described, in his 

 " Synopsis Fungorum in America B or eali media digen- 

 tium" the destruction of both wild and cultivated varieties 

 by the disease. The distinguished entomologist, Dr. T. 

 W. Harris, in his earlier writings advocated the view that 

 the knot is caused by insects ; but later f he mentions the 

 fungus, which, he says, is sure to appear on the knots, 

 and never elsewhere, though he does not commit himself 

 fully to the theory that the disease is of fungous origin. 

 In 1862 the editor of the " Gardener's Monthly," Mr. Thos. 

 Meehan, took strong ground in favor of the fungous origin of 

 the disease, and for several years following a spirited discus- 

 sion of the subject was carried on by various correspond- 

 ents in the columns of his journal. At« about the same time 

 it was logically argued, in the " Country Gentleman," that, 

 even though insects were found in ninety-nine knots, the 

 finding of the hundredth one free from them would be suf- 

 ficient to show that they could not be the cause of the dis- 

 ease. 



Mr. C. F. Austin gave i what appear to have been the 

 first account and illustrations of the microscopic structure of 

 the knot fungus. Entomological writers now began rap- 

 idly to accept the fungus theory of the origin of the knots, 

 as is shown by papers from Glover, § Walsh j| and Riley. 1[ 

 Walsh gives at considerable length an account of the sup- 

 posed structure and life history of the knot fungus, so 

 wholly unlike what we now know of it that it is impossible 

 to conjecture what he could have seen. Up to 1872 knowl- 

 edge of the fungus was very meagre, and confined to the 

 winter spores to be described later. In that year Prof. 



* Synopsis Fungorum Carolina? superioris, no. 134 (1821). 



t Insects Injurious to Vegetation, 2d ed., p. 69 (1852). 



+ Amer. Agriculturist, 1863, p. 113. 



§ U. S. Agric. Report, 1863, p. 572. 



|| Practical Entomologist, Vol. I, p. 48, and Vol. II, p. 63 (1866-67). 



H Gardener's Monthly, November, 1866, p. 331. 



