By Thomas Andrew Knight, Esq. 181 



subject, in the same season, that I had not any expectation 

 of succeeding in an attempt of that kind ; but I thought it 

 not improbable, that I might succeed in communicating this 

 disease to seedling plants of the Pear tree, having long ago 

 satisfied myself that the species of fungus, which forms the 

 mildew of wheat, always rises from the root of the plant. 



I have many years been in the habit of raising annually 

 Pear trees from seeds, with the hope and expectation of ob- 

 taining new and hardy varieties for the dessert in winter ; 

 which may succeed without the protection of a wall ; and as 

 the means I employ to obtain seeds well calculated for my 

 purpose, necessarily cost me a good deal of time and labour, 

 I have always planted them in pots, and in the kind of mould 

 which long experience has pointed out to me as the best. 

 This I have always obtained, at the period of sowing the 

 seeds, in January or February, from the banks of a river 

 at some distance from my garden ; and in this mould my 

 seedling Pear trees always sprang up, and remained during 

 the first season, perfectly free from disease. In the Spring of 

 1813, a portion of this mould, which I did not want, was in- 

 tentionally placed very near some Hawthorns and Pear trees, 

 upon which the Lycoperdon cancellation abounded, where 

 it remained till the Spring of 1814, when it was put into pots, 

 and new seeds deposited in it. These sprang up as usual, 

 and remained in perfect health till the end of May or be- 

 ginning of June; when the fungus presented itself upon 

 almost all the first true leaves of the plants, which leaves 

 had composed the plumules of the seeds. 



That the fungus, in this case, rose from the ground, will, I 

 think, scarcely be questioned ; but it is necessary to state, 



