32 THE SCIENTIFIC PRINCIPLES. 



Physiologie' — and covering a still wider range of 

 subjects, bringing the information on the various 

 points up to date, and going into much detail as to the 

 methods of research, as well as to the results obtained. 

 In these volumes, those who desire it will be able to 

 examine for themselves the evidence upon which many 

 important conclusions have been based. 



A few of the works by English authors which have 

 appeared within the same period, it may be well to 

 enumerate. Among them are Johnston's * Lectures on 

 Agricultural Chemistry and Geology/ first published 

 in 1844; and his 'Experimental Agriculture/ pub- 

 lished in 1849. His successor, Dr. Anderson, also 

 published, in i860, a work entitled — 'Elements of 

 Agricultural Chemistry/ 



New editions of Johnston's work have since been 

 published by Dr. C. Cameron ; the first of these, the 

 tenth of the original work, appearing in 1877. 



Perhaps the most compendious record of the results 

 of the Continental investigations up to the time 

 of its publication, which has appeared in our own 

 language, is that by Professor S. W. Johnson, of Yale 

 College, Newhaven, Connecticut, in two volumes, 

 entitled ' How Crops Grow/ and ' How Crops Feed/ 

 The results of the German experiments on the 

 Feeding of Animals have also been summarised by 

 Dr. Armsby, in a volume published in America, and 

 entitled — ' Manual of Cattle-Feeding/ 



Neither in the works above referred to, nor in the 

 reports of the Continental Experimental Stations, do 

 we find the record of many systematic or long con- 

 tinued field-experiments. We have, however, the 

 example of Boussingault, and the opinions of Sir 

 Humphrey Davy, Liebig, and Daubeny, as to the great 

 importance of such methods of agricultural research. 



