Charles B. Lipman 171 



The investigations of Loew and Nageli 1 led them to make the 

 statement that elementary nitrogen is an unsatisfactory source 

 of that element for molds. Lawes, Gilbert and Warrington 2 

 could not show any fixation of nitrogen by some soil molds since 

 analyses of soil, in which these molds were, showed no increase 

 of nitrogen. 



Winogradsky has reported negative results in experiments with 

 an Aspergillus species, and Czapek 3 has likewise reported nega- 

 tive results with Aspergillus niger and criticised the results of 

 Puriewitsch and Saida, especially the latter, on the ground that 

 the amounts of nitrogen fixed may have been due to errors in the 

 nitrogen determinations. Gerlach and Vogel 4 reported negative 

 results with a yeast experimented with by them. 



To all of these doubtful or negative results on the fixation of 

 nitrogen by yeasts, molds and other fungi, should be added the 

 results of investigations very recently carried out by Duggar and 

 Knudson 5 at Cornell University in which it is claimed that no 

 nitrogen fixation was observed, except to a very slight extent 

 in cultures of Aspergillus niger. 



Opposed to these negative results we have the positive results 

 of several investigators in which we find a description of marked 

 powers of fixing nitrogen attributed to the yeasts and molds experi- 

 mented with. Berthelot 6 noted gains of nitrogen in cultures of 

 Aspergillus niger, Alternaria tennis and Gymnoascus, but only 

 the cultures of A Uernaria tennis were pure. Puriewitsch, 7 however, 

 worked with pure cultures of Aspergillus niger and Penicillium 

 glaucum and in addition to all other precautions to exclude bac- 

 teria from these cultures he added some phosphoric acid to his 

 culture solution which latter consisted of 100 cc. of water, 0.4 

 gram of monopotassium phosphate, 0.4 gram of calcium chloride, 

 0.2 gram of magnesium sulphate, 3 grams of tartaric acid, vary- 

 ing amounts of dextrose and small amounts of ammonium nitrate. 



l Sitzungsber. d. mathem. physik. Klasse d.Akad. Miinchen, x, p. 280. 

 t Journ. Chem. Society, Transactions, xliii, p. 208. 

 *Beitr. z. chem. Physiol. und PathoL, ii, p. 559, 1902. 

 4 Loc. cit. 



'Abstract in Science, Feb. 3, 1911, of a paper read before the Botanical 

 Society of America. 



6 Chimie vegetale et agricole, i, Paris, 1899. 

 7 Ber. d. deutsch. bot. Ges., xiii, p. 339, 1895. 



