The Scie^itific Agriculture of the Period. 291 



Sprouts that are contained in each. Grain to the End they 

 may dilate and unfold themselves. The second Action of 

 these Salts is to serve each Grain of Corn, as it were, instead 

 of a Loadstone, to attract the Nitre of the Earth, which the 

 Subterranean Fires have reduced and driven into Steam and 

 Vapours in the low and middle Region of the Air for the 

 Nourishment of Vegetables and of Animals." But to TuU, 

 who had often walked into his fields and tracked the roots of 

 plants throughout their ramifications in the soil, the idea 

 about the loadstone was untenable. Here, in fact, occurs one 

 of those numerous instances where theory is set right by 

 practice ; and it is well to be sceptical of results whenever 

 we find the one unsupported by the other. 



Tull was by nature inclined to exaggerate the importance 

 of the mechanical factor in vegetation, and to under-estimate 

 the chemical. Considering the obscurity which pervaded the 

 atmosphere of the laboratory at this period of history, and 

 the wild and fallacious doctrines which emanated from the 

 analyst's crucible, it was perhaps as well for agriculture that 

 he had this predisposition. Unfortunately it ultimately in- 

 duced him to discard the use of all fertilisers, and to trust 

 entirely to mechanical means in the system which has made 

 his name so famous. " Plants differ," he says, " as much from 

 one another in the Degrees of Heat and Moisture they require, 

 as a Fish differs from a Salamander." " Our Earth," he says 

 in another place, " when it has in the Stove the just Degree 

 of Heat that each Sort of Plants requires, will maintain 

 Plants brought from both the Indies." But when he dis- 

 cusses the effects of a manure on plant life, it is only to 

 point out its defects. He praises the action of florists in 

 excluding dung from their flow^er gardens, and wishes to 

 prohibit its use in the kitchen garden as well. Because the 

 carrot bred on the dunghill has not the same sweet relish 

 which the field carrot affords, he adopts the extreme view 

 that all vegetables are best without any manure at all. It 

 encouraged worms, bred vermin, harboured the seeds of weeds, 

 and emitted effluvia injurious to animal life. If used at all, it 

 should be allowed to rot sufficiently long as to get rid of its 



