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XLIV. On the Mode of Propagation of the Lycoperdon can- 

 cellatum * a Species of Fungus, which destroys the Leaves 

 and Branches of the Pear Tree. By Thomas Andrew 

 Knight, Esq. F.R.S. $c. President. 



Read December 5, 1815. 



I had the honour, two years ago, to address to the Horticul- 

 tural Society some observations upon the propagation of 

 these supposed species of parasitical plants, which, under 

 the name of Fungi,+ appear as diseases upon other living 

 plants : and of other supposed species of the same tribe, which 

 decompose and feed upon organic substances, that have 

 ceased to live. In the present communication, I shall endea- 

 vour to shew, that one of these, at least, is a parasitical 

 plant, which propagates like other plants, by seeds. 



I observed, about seven years ago, a disease upon a few of 

 the leaves of one of the Pear trees in my garden at Downton. 

 Bright yellow spots, from which a small quantity of liquid 

 exuded, appeared upon the upper surfaces of the leaves in 

 June ; and subsequently, several conic processes, about one 

 third of an inch in length, were protruded from the same 

 parts, but from the opposite surface, of each leaf; and from 

 these a large quantity of brown impalpable powder, con- 

 sisting of very minute globular bodies, was discharged in 



* I am indebted for the name of this species of fungus to the extensive infor- 

 mation of Mr. Dickson, who referred me to the Flora Danica for a delineation 

 of it: but Sir Joseph Banks subsequently shewed me a drawing of it by Mr. 

 Bauer, which is much more elal>orate and correct. 



f Sec page 82 of this volume, 



