268' Thoughts on the Smut in Jf^heaf, Anig,. 



greateft refpefl from farmers (I mean the profeflbr of agricul- 

 ture in the univerfity of Edinburgh) concerning the nature of 

 fmut, is generally known. He is of opinion, that fmut is a 

 difeafe in corn, fomcwhat fimilar to cancer in the human body, 

 and that it is communicated by a fort of inoculation, from the 

 attachment of the fubllance of difeafcd cars to found ones ; the 

 plants from which, are ai7c£^ed by this difeafe in their whole 

 conftitution, the difeafe being particularly manifefted in the 

 ears. If I have not dated this corretlly, Dr Coventry will have 

 the goodnefs to put me right. Although it may be difficult to 

 afcertain its precife naturr, I think there can be little doubt of 

 fmut being a difeafe of the conftitution of the plant. Indeed, 

 the practice of pickling in a manner proves it, as this procefs is 

 intended to dellroy the caufe of infe£lion, which appears to 

 have no influence on the feed till it begins to germinate. A ha- 

 bit I ufed to have of pulling unripe corn for the fake of chew- 

 ing the fucculent part of the ftalk under the uppermoft knot, 

 led me to difcover, that from the very firfb formation of the ear, 

 long before it breaks its confinement, it is afTefred by the dif- 

 eafe, while externally the plant appears very vigorous. This 

 circumftancc, at any rate, precludes any fuppofition of blight 

 being the caufe of fmut, and alfo difproves that fmut is occa- 

 fioned by paralitica] pknts or infefts. The one could not grow 

 without the accefs of air, nor could the latter be produced with- 

 out fome apparent injury being done to the plant from without. 

 That the difeafe (hould appear only in the ears of corn, is not 

 more wonderful than that the dreadful conftitutional malady, the 

 fcrophula, iliould be confined to the glands. Until I obtain fur- 

 ther information on this fubje^t from obfervation and experi- 

 ment, I (hall retain the opinion of Dr Coventry as I have ftat- 

 cd it, and confider the fubftance of fmut as nothing elfe than 

 the vitiated juices of the plant altering what was intended to 

 form wholefome grain. This letter has become longer than I in- 

 tended 5 but ail apology for any thing which may, in the fmal- 

 left degree, aflift the object of your Magazine, is unneceflary to 

 you. I remain, with every good wifh, 



Your mod obedient and humble fervant, 



Coulf i^th March 1804. George S. Mackenzie. 



T^ 



