PEARS. 175 



pie, is doubtful, in the opinion of some experienced 

 cultivators that species of blight, which is sometimes 

 called the fire blight, frequently destroys trees in the 

 fullest apparent vigour and health, in a few hours, 

 turning the leaves suddenly brown, as if they Lad 

 passed through a hot flame, and causing a morbid 

 matter to exude from the pores of the bark, of a black 

 ferruginous appearance ; this happens through the 

 whole course of the warm season more frequently 

 in weather both hot and moist, affording reason to be- 

 lieve that it arises from the rays of the sun operating 

 on the vapour, or clouds, floating in the atmosphere, 

 either by concentration or reflection. It generally, 

 though not always, is perceived most in confined pla- 

 ces: certain kinds, and particularly that most exquisite 

 of our winter pears, the St. Germain, seems peculiar- 

 ly liable to this species of blight. I have in twenty 

 years lost upwards of fifty trees in the fullness of vig- 

 or sometimes in the most open airy situations, and 

 in every kind of soil. From repeated observation of 

 the kinds most liable to this malady, I have been led 

 to believe, that it is somewhat connected with a prin- 

 ciple which appears to be considered as a sound one, 

 by the most judicious European writers, when trea- 

 ting of apple trees, that is the long duration of the va- 

 riety. It is certain, that natural trees, continually 

 .springing up from seed, are seldom attacked by this 

 Disease: and the Seckle pear, generally supposed to 



