OF SOME EDIBLE AMERICAN FUNGI. 147 



bility of this substance existing in combination with fatty 

 acids in the fungi.* 



Crude fiber was determined according to Wiley's method,f 

 in the residue left after extractions with ether. 



Total nitrogen was found by the Kjeldahl method, duplicate 

 determinations always showing a very close agreement. It is 

 customary in agricultural analysis to express the results thus 

 obtained, and multiplied by the factor 6.25, as " crude pro- 

 tein." The latter term is thus made to include albuminoids 

 and extractive bodies as well as the proteids proper.! Not 

 only do these individual groups possess quite variable signifi- 

 cance as foods, but this investigation has further demonstrated 

 that such calculations may lead to quite erroneous conclusions. 

 In the mushrooms, at least, a considerable part of the nitrogen 

 probably exists as non-proteid nitrogen, a portion even belong- 

 ing to the so-called crude-fiber, or cellulose elements of the 

 fungi. In a large number of our analyses an attempt has 

 been made to separate the nitrogen of the extractive bodies 

 (amide-nitrogen, etc.) by treating a portion of the material 

 repeatedly with boiling 85 per cent alcohol, so long as any- 

 thing could be removed. The nitrogen content of the alco- 

 holic extract having been determined, and then calculated on 

 the material used, is designated as extractive nitrogen. \\ The 

 amount of alcohol-soluble material was ascertained at the same 

 tune, by filtering the undissolved extraction residues on 

 weighed filters and drying at 105 C. to constant weight. 

 The difference between the total nitrogen and extractive nitro- 

 gen is provisionally given as protein nitrogen, though, as 

 stated above, there is at present no justification for expressing 



* Cf. Hiirthle, K., Ueber die Fettsaure-Cholesterin-Ester des Blutes. 

 Zeitschr. fur physiol. Chemie, 1896, xxi, p. 362. 



t Wiley, Agricultural Analysis, 1897, iii, p. 304. 



J Cf. Atwater, W. 0., Foods : Nutritive Value and Cost. Farmers' Bulle- 

 tin, No. 23, pp. 6, 6. U. S. Dept. of Agriculture, 1894. 



Winterstein, Berichte der deutsch. botan. Gesellsch., xi, p. 441; also 

 Zeitschr. fur physiol. Chemie, 1894, xix, p. 621 ; 1896, xxi, p. 134 ; Gilson, 

 La cellule, xi, ler fascicule. 



U Cf . Morner, C. Th., Zeitschr. fur physiol. Chemie, 1886, x, 506. 



