172 Nitrogen Fixation by Yeasts 



Gains of nitrogen were noted in all cultures. It is interesting 

 however, to observe in his results, the large differences in the 

 amounts of nitrogen fixed by the same organism in duplicate cul- 

 tures. Saida 1 not only confirmed the results of Puriewitsch on 

 Aspergillus niger, but showed that a distinct nitrogen fixing power 

 was possessed by Mucor stolonifer, Endococcus purpurascens, 

 and Phoma betae. No gains of nitrogen, however, were noted by 

 the same investigator in cultures of Acrostalagmus cinnibarinus, 

 Monilia variabilis and Fusisporium moschatum. A. Koch 2 claims 

 that he and other investigators in repeating the experiments of 

 Puriewitsch and Saida could not obtain any fixation of nitrogen, 

 but calls attention to the fact that his results must not be taken 

 as proof of the questionable purity of the cultures used by Purie- 

 witsch and Saida nor yet of any error in the work of the last named 

 investigators but rather to a change in the character of the organ- 

 isms in old cultures as indeed this has often been noted in cultures 

 of Azotobacter which after long standing seemed to have only a 

 feeble nitrogen fixing power. This is an interesting observation 

 which agrees with* a similar one made by the writer in the experi- 

 ments described below. 



Frank 3 showed distinct gains of nitrogen in work carried out 

 with different species of Penicillium, amounting in one case to 

 3.5 mg. of nitrogen in 65 cc. of nitrogen-free sugar solution in 

 an incubation period of ten months. Remy 4 also showed fixation 

 of nitrogen by three out of twenty-five molds which he tested 

 and among these was Aspergillus niger which fixed 10 mg. of nitro- 

 gen on 20 grams of dextrose as a source of energy. To these must 

 also be added the investigations of Ternetz 5 who found in working 

 with five species of Phoma that the latter possessed a pronounced 

 nitrogen fixing power, noting in one case a fixation of 22 mg. 

 of nitrogen per gram of dextrose. The same investigator noted 

 gains of nitrogen also in cultures of Penicillium glaucum and Asper- 

 gillus niger amounting in the latter case to 2.71 mg. nitrogen per 

 gram of dextrose. 



l Ber. d. deutsch. bot. Ges., xix, p. 107, 1901. 

 2 Handbuch der technischen Mykologie, Jena, iii, 1907. 

 *Landw. Jahrb., xxi, p. 7, 1892; Bot. Zeitung, li, p. 146, 1893. 

 4 Verh. d. Ges. deutsch. Naturf. und Aerzte, Ixxiv, i, p. 221, 1902. 

 *Ber. d. deutsch. bot. Ges., xxii, p. 267; Jahrb. f. wissen. Botanik, xliv, 

 1907, p. 353-408. 



