.236 Latham : Assimilation of Sterigmatocystis 



of Barnard College with the aid and advice of Professor Richards, 

 to whom the writer is pleased once more to be able to acknowl- 

 edge indebtedness and gratitude. A grant from the Esther 

 Herrman Fund supplied some of the special apparatus used in 

 prosecuting the work. 



In 1895 Puriewltsch * published the results of an investigation 

 on the nitrogen-fixing power o( Aspergillus niger {Sterigmatocystis^ 

 and Penicilliitm glaiLciDHy concluding that both organisms are able 

 to bring uncombined nitrogen into chemical union, the amount so 

 combined being in direct proportion to sugar supply and bearing 

 no definite relation to the dry weight of the fungal felt. This 

 work has been brought to question by various commentators f 

 because of the small amount of nitrogen determined in analyses 

 and the large chance of error inherent in the Kjeldahl method. 

 Puriewitsch;|; in his cultures used phosphoric acid in minute quan- 

 tity to inhibit the growth of any nitrogen-fixing bacteria, not being 

 sure, it seems, of his stock of the fungus. It has been indicated 

 by the results that follow that the presence of this phosphoric 

 acid will account for the small amount of nitrogen combined by 

 the fungus, since the mycelium was stimulated by the acid and the 

 ability to fix atmospheric nitrogen at the same time diminished. 



Saida § has recorded a gain in total nitrogen in compound when 

 w;orking with Aspergillus ; Winogradsky || had none. Berthelot^i 

 had written in 1893 that he found a fixation of nitrogen by Aspe?'- 

 gillus niger ^ Alternaria tennis^ and Gyninoascus ; but of these only 

 the Alteruaria culture was pure and there the gain reached as high 

 as 98 per cent, of the original nitrogen content. Brefeld ^^ investi- 

 gated the action of Ustilago^ which he found did not assimilate free 



* Puriewitsch, K. Ueber die Stickstoffassirailation bei den Schimmelpilzen. Ber. 

 Deuts. Bot. Gesells. 13: 342. 1895. 



f Lafar, P\ Handbuch der Technischen Mykologie 3 : 1-69. I904-1906. 

 -^ Czapek, F* Biocbemie der Pflanzen 2 : 125. 1905. 

 -*- Jost, L. Plant Physiology, 235, 1907, [English translation.] 



J Puriewitsch, K, Loc, cit. 



Saida, K. Ueber die xA.ssimilation freien Stickstofts durch Schimraelpilze. Ber. 

 Deuts, Bot. Gesells. ig : 107. 1901. 



II See Lafar, F. Handbuch der Technischen Mykologie 3:11. 

 ^ \ Berlhelot, M. Recherches nouvelles sur les microrganismes fixateurs de Pazote. 

 Comptes Rendus 116 : 842, 1893. 



** Brefeld, O, Versuche uber die Stick stoffaufnah me bei den Pflanzen. Centralb. 

 fur Bakt. II. 8 : 24. 1902, 



