178 CULTURE OF FAEM CROPS. 



on meagre, impure food, it is induced to consume a greater 

 quantity, to make up as much as possible for the deficiency 

 of quality ; and the consequence is, a distension of the 

 stomach and bowels, and this is often followed by a po- 

 verty and corruption of the fluids, which produces disease 

 and debility; and the body is wasted by eruptions, and 

 becomes a prey to vermin. And when an animal (more 

 particularly during parturition) is glutted with grass and 

 rich food, a surfeit is the consequence, and it is subjected 

 to a stagnation of the fluids, inflammations, and eruptions, 

 which often end in mortification and death ; and plants, 

 under the same circumstances, are subject to the same 

 consequences. 



" These observations will be found correctly to apply to, 

 and to afford a clear exemplification of, the rust, or black 

 blight in wheat. 



"On this subject Sir John Sinclair says, 'It appears, 

 from an able paper written by a distinguished naturalist 

 (Sir James Banks), that this disease is occasioned by the 

 growth of minute parasitical fungus or mushrooms on the 

 leaves, stems, and glumes, or chaff of the living plants; 

 and that the roots of the fungus, intercepting the sap in- 

 tended by nature for the nutriment of the grain, render 

 the grain lean and shrivelled, and, in some cases, rob it 

 completely of its flour. JN"or is that all ; the straw becomes 

 black and rotten, unfit for fodder, or little better than 

 a caput mortuum, possessing neither strength nor sub- 

 stance.' 



" Again, ' Several of the accidents above enumerated 

 may contribute to the production of rust ; but there are 

 two additional circumstances which likewise tend to pro- 

 mote it. First, Having the land in too rich a state for 

 corn crops, and, secondly, when too frequent a repetition 

 of crops of wheat takes place.' 



" It has been well observed, that when crops intended to 

 ripen their seed are objects of culture, there is not only 

 wanted a degree of vigour and luxuriance in the plants 

 sufficient for the purpose, but if the fertility of the soil be 



