OF AGRICULTURE. 43 



made to determine the amount of water given off by 

 plants during their growth. In this way various 

 plants, including representatives of the gramineous, 

 the leguminous, and other families, have been ex- 

 perimented upon. Similar experiments have also 

 been made with various evergreen and deciduous 

 trees. 



Having regard to the difference in the character 

 and amount of the constituents assimilated by plants 

 of different botanical relationships, under equal ex- 

 ternal conditions, or by the same description of 

 plants, under varying conditions, observations have 

 been made on the character and range of the roots of 

 different plants, and on their relative development of 

 stem, leaf, &c. In the case of various crops, but 

 more especially with wheat and beans, samples have 

 been taken at different stages of growth, and the 

 composition determined, in more or less detail, some- 

 times of the entire plant, and sometimes of the 

 separated parts. In a few cases, the amounts of dry 

 matter, ash, nitrogen, &c, in the above-ground 

 growth of a given area, at different stages of 

 development, have been determined. The amounts 

 of stubble of different crops have also occasionally 

 been estimated. 



Experiments were made for several years in 

 succession to determine whether plants assimilated 

 free or uncombined nitrogen, and also various col- 

 lateral points. Plants of the gramineous, the 

 leguminous, and of other families, were operated 

 upon. The late Dr. Pugh took a prominent part 

 in this enquiry. 



Obviously, an investigation of the scientific prin- 

 ciples of Agriculture would be incomplete if it were 



