76 



collected at Rotbanisted. The late Dr. Voeleker also determined the 

 combined nitrogen, and likewise the incombu.stible constituents, in Go 

 samples of the drainage waters; and Dr. W. J. Russell has determined 

 the sulphuric acid in some of the monthly mixed samples of rain water. 



"The nitrogen existing as nitric acid, sonietimes that in other forms, 

 and also some other constituents, are and for some time past have been 

 determined periodically in tlie Rothamsted laboratory, in both the rain 

 and the various drainage waters." 



For several years experiments were made to determine the amount 

 of water given off by graminacecuis, leguminous, an«l other j)lants during 

 their growth. Similar experiments have .ilso been made with various 

 evergreen and deciduous trees. 



"Having reganl to thedilference in the character and amount of the 

 cofistituents assimilate*! by plants of different botanical relationsiiips 

 under equal external corulitions, or by the same descri[)tion of plants 

 under varying conditions, observations have been made on the character 

 and range of the roots of different i)lants,an<l on their relative develop- 

 ment of stem, leaf, etc. In the case of various crops, but more especially 

 with wheat and beans, samples have been takeu at different stages of 

 growth and the eompositioii 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, etc., in tlie above 

 ground growth of a given area, at different stages of developnuMit, 

 have been determined. The amounts of stubble of different crops have 

 also occasionally been estimated." 



Among the most widely known of the experiments at Rothamsted 

 are those with reference to the assimilation of free nitrogen by plants, 

 commenced in 1857 and conducted for several years. The conclusion 

 arrived at, that our agricultural plants do not themselves directly 

 assimilate the free nitrogen of the air by their leaves, has been gen- 

 erally acce]>ted. Since the experiments of Atwater have vshown that 

 the free nitrogen of the air is assimilated by leguminous plants, and 

 those of Hellriegel and others have shown that this assimilation takes 

 place through the aid of microorganisms, either within the soil or in 

 symbiosis with i)lants of a liigher order, in which .process the root 

 tubercles of these plants play an important part, experiments at 

 Rothamsted have confirmed the results obtained elsewhere. 



" Experiments with the animals of the farm were commenced early in 

 1847, and have been continued at intervals up to the present time. 



" The following points have been investigated : 



"(I) The amount of food and of its several constituents consumed in 

 relation to a given live weight of animal within a gi\eu time. 



"(2) The amount of food and of its several constituents consumed to 

 produce a given amount of increase in live weight. 



"(.3) The i>roportion and relative development of the different organs 

 or parts of different animals. 



