180 CHARLES OSCAR CHAMBERS 



The details of the work done by Duggar and Knudson" 

 are not available but the general tone is toward the discredit 

 of the results of Miss Latham. 



The work of Pennington^^ though not yet exhaustive, being 

 comparatively new, seems however to have been carefully done 

 and merits much consideration. His first work was done upon 

 Aspergillus niger and seems to have been stimulated by the 

 apparently incredible gains shown in the reports of Miss Latham. 

 As already mentioned he is one of the few to have employed the 

 colorimetric method, and that only sparingly. His work was 

 not known to me until near the end of my own. He has not 

 in any sense made use of the micro-method. 



The field seems to be open for workers and there are many 

 gaps yet to be filled. 



METHOD 



The micro-method offered a number of perplexing and dis- 

 couraging difficulties at the outset, most of which had to be 

 met and solved anew, even though they were well known in the 

 old method, as they had never before been tested in this con- 

 nection. On this account it seemed best to follow at first the 

 methods of the earlier investigators and still followed, so far as 

 I am aware, by all the later ones. 



Accordingly, I followed essentially the method of Purie- 

 witsch^^ and Ternetz^^ both as to kinds of media and method of 

 determination of nitrogen, checking by Kjeldahl, the theoretical 

 amount of nitrogen furnished in the cultures and making de- 

 terminations both before and after growth. But it was the 

 unusual gains reported by Latham ^^ which offered the strongest 



^" Duggar, B. M. and Knudson, L., Relation of certain fungi to nitrogen fix- 

 ation, Science 31: 191. Feb. 1911. 



1^ Pennington, L. H., Upon the assimilation of atmospheric nitrogen by fungi. 

 Bull Torr. Bot. Club 38: 135-139. 



Pennington, L. H., Can Fusaria assimilate free nitrogen? Proc. Mich. Acad. 

 Sci. 10: 50, 1908. 



'- Puriewitsch, I. c. 



1' Ternetz, I. c. 



1^ Latham, I. c. 



