CHAPTER XII 



SOURCES OF KNOWLEDGE 



The foregoing chapters embody many statements of 

 principles and facts which have been made positively 

 and without modification. To quite an extent these 

 are based upon the conclusions of scientific men, i.e., 

 conclusions which have been reached after such study 

 of the problems involved as is competent to secure ac- 

 curate information. In some cases this study has been 

 severe and long continued, having been carried on by 

 the use of methods and apparatus capable of the most 

 precise measurements. Moreover, in the investigations 

 of science an effort has been made to proceed logically, 

 so that the results attained shall not be fallacious. Not- 

 withstanding the fact that a great deal of oiu- knowledge 

 is the result of an earnest and impartial search after 

 truth, under conditions especially favorable to its dis- 

 covery, many persons are disposed to give more credit to 

 traditions and conclusions of practice than to the care- 

 fully prepared verdicts of science. It may not be out of 

 place, therefore, to present in this connection some of the 

 considerations and methods which have to do with the 

 acquisition of knowledge concerning animal nutrition, 

 for this may aid us to appreciate the value of well-estab- 

 lished facts and to exercise caution in accepting the 

 verdicts either of science or of practice before they are 

 thoroughly justified. 



There are three general ways in which we may be 

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