OF AGRICULTURE. 13 



Although his conclusions on the subject have doubt- 

 less undergone modification since that time, the work 

 itself marked a great advance on previously existing 

 knowledge and modes of viewing the question. 



In 1837 Boussingault published papers on the 

 amount of gluten in different kinds of wheat ; on 

 the influence of the clearing of forests on the diminu- 

 tion of the flow of rivers ; and on the meteorological 

 influences affecting the culture of the vine. In 1838 

 he published the results of an elaborate research on 

 the principles underlying the value of a rotation of 

 crops. He determined by analysis the composition, 

 organic and inorganic, of both the manures applied 

 to the land, and the crops harvested. In his treat- 

 ment of the subject he evinced a clear perception 

 of the most important problems involved in such 

 an enquiry ; some of which, with the united labours 

 of himself and many other workers, have scarcely yet 

 received an undisputed solution. 



Thus, in the same year (1838), he published the 

 results of an investigation on the question whether 

 plants assimilate the free or uncombined nitrogen 

 of the atmosphere ; and although the analytical 

 methods of the day were inadequate to the decisive 

 settlement of the point, his conclusions were in the 

 main those which much subsequent work of his own, 

 and much of others also, have served to confirm. 



In subsequent lectures I shall have to refer in 

 some detail to the various investigations here 

 alluded to. 



As a further element of the question of the chemical 

 statistics of rotation, Boussingault determined the 

 amount and composition of the residues of various 

 crops ; also the amount of constituents consumed in 

 the food of a cow, and of a horse, respectively, and 



