INTERNAL WORK. 393 
certainly seems open to question, however, whether in this case also 
other properties than those expressed by the percentage of crude 
fiber may not materially affect the result,* and it will be wise, until 
the subject receives further investigation, to accept their compu- 
tations as tentative and approximate.t 
* Compare Kellner’s results on cattle, Chapter XIII, §1. 
+ A somewhat extended critique by Pfeiffer of these researches, together 
with replies by Zuntz & Hagemann, will be found in Landw. Vers. Stat., 54, 
101; 55,117; 56, 283 and 289. 
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