CROPS. 455 



it could dispose of, the vessels burst, and the plant in truth dies 

 of repletion. My own experience and observation seern fully to 

 confirm this theory. The blight of mildew is a different affec 

 tion. The causes are not well ascertained, and the preventives 

 equally undetermined. A distinguished German clergyman or 

 pastor, and I may be allowed to add, in passing, that to no pro 

 fession has agriculture been more indebted for its improvements, 

 after long and careful observation, is of opinion, that three causes 

 may produce it the state of the atmosphere, when the plant is 

 in a particular stage of its growth ; an unfortunate choice of the 

 time of sowing ; or the particular condition of the soil. He has 

 found that, in the same neighborhood, the wheat in some fields 

 has been badly affected, while in others it has escaped the mil 

 dew. This circumstance seems opposed to the atmospheric 

 theory ; yet in the same country, the state of the atmosphere 

 may be different in different positions and aspects of the field. 

 Every one must have experienced this in passing along a public 

 road in an evening ; without a thermometer we become sensible, 

 in different places, to great variations of temperature. With us 

 in New England late-sown peas seldom escape the mildew, or 

 what is called the blue mould, which has seemed to me attributa 

 ble to the heat of our autumnal midday sun, followed by the 

 chilliness of our autumnal evenings and their abundant dews. 

 The same theory may account for the facts which he mentions 

 in regard to sowing. He has sown wheat in September, which 

 has suffered slightly from mildew; in October, in the same year, 

 which has suffered severely ; in November, which has entirely 

 escaped. The circumstances in these cases are not all given. 

 It is, therefore, difficult to make up a judgment ; but one would 

 infer that the late-sown wheat was carried beyond the suscepti 

 ble season. The influence which the condition of the soil may 

 have upon the health of the plant in this matter, or how far it 

 may be affected by the manure employed, are points not deter 

 mined. In one district in Alsace it is said the farmers find their 

 wheat liable to suffer from mildew, when it follows clover 

 which has been highly manured ; but the manure customarily 

 used in this case is the manure of hogs, to which some are dis 

 posed to attribute this result. Nothing seems more uncertain, or 

 rather more imperfectly defined, than agricultural facts, excepting 

 it be agricultural theories. In order safely to deduce a valuable 



