535 



nary circumstances, deranging the vegetable functions, in the same 

 manner as minute parasites infest different parts of the animal 

 structure. A. good opportunity occurred casually in the Botanic Gar- 

 den of affording data to judge of the fearful consequences of the corn 

 fungi when no means are used to check them. In cultivating small 

 samples of as many of the different kinds of the cereal grains as we 

 could procure, constantly on the same piece of ground, without 

 change of seed, the samples which were originally clean soon became 

 infected, which increased every subsequent year, until at length the 

 varieties which had been longest cultivated became so completely co- 

 vered with mildew and smut, that out of the produce of three square 

 yards or so, we could get scarcely a single head free from the fungi. 

 In this instance there is reason to suppose that the spores were pro- 

 pagated by inoculation on the seed, and also that they were imbibed 

 through the cellular tissue of the rootlets, along with the water con- 

 taining the nutritive matters afforded by the soil. 



Many more interesting cases might be brought forward to show the 

 extensive operations which these minute plants perform in the vege- 

 table economy, which I cannot follow further at present. In the fore- 

 going observations I have endeavoured to treat the subject in rather a 

 popular manner, avoiding such scientific details as would necessarily 

 be tedious, if not uninteresting, to those who have not hitherto turned 

 their attention to such investigations. I believe the only cure yet 

 known for smut and mildew, is steeping the seed, if grain, in chemi- 

 cal solutions calculated to destroy the vegetative principle of the 

 spores of the fungi, with a proper rotation of cropping. My object in 

 noticing the matter in connexion with the foregoing part of this pa- 

 per, has been with a view of directing the attention of practical gentle- 

 men to its importance. The fungi which have so uniformly accom- 

 panied the potato-disease, prove that they have some connexion with 

 it, as I do not think I have seen a single tuber on which the decay 

 had progressed to any considerable extent, but what became more or 

 less covered with the Psilonia rosea of Berkeley. At a late meeting 

 of the Highland and Agricultural Society of Scotland, a paper was 

 read on this subject by Mr. Goodsir, when a practical gentleman who 

 was present, stated that he had been for a number of years in the 

 habit of steeping a bole* of wheat in three quarters of a pound of sul- 

 phate of copper (or bluestone) dissolved in water, which he had found 



* Six bushels. 



