176 CHARLES OSCAR CH.ANIBERS 



jMoreover, the method, which will be designated as the micro- 

 method, is adapted to a very small amount of the sample, using 

 large test-tubes for digestion in place of the special flasks em- 

 ployed in the Kjeldahl method. This makes it possible to 

 digest the cultures of fungi in the tubes in which they were 

 grown and thus avoid the possibility of loss by transfer from the 

 cultiu'e flasks to digestion flasks, as usually practiced in the 

 Kjeldahl method. 



These features, together with others to be mentioned later, 

 lend facility as well as accuracy to the micro-method and make 

 it possible to handle a large number of cultures with convenience 

 and speed, both matters of great importance in makmg determi- 

 nations of this character. It is the successful adaptation and 

 application of the above fe^itures of a new method to an old 

 problem and a partial solution of the problem that seemed to 

 justify a pubhcation of the results and a description of the method 

 at this time, although a more exliaustive and more exact test 

 will be necessary to settle even a small part of so large a problem 

 as the one here represented. 



HISTORY AND DISCUSSION 



In a separate table is given a tabulated hst of the chief in- 

 vestigators on nitrogen-fixation by fungi, together wiih the 

 results of their work 'on Aspergillus niger. This and Penicillium 

 glaucum have been the chief fungi used for this kind of investi- 

 gation as well as for the other problems of nutrition. For tliis 

 reason Aspergillus is of special interest. 



The earliest investigator of whom we have any record, and 

 hence of liistoric mterest, is Jodin^ whose work was done before 

 the Kjeldahl method was known and is therefore lacking in 

 scientific value. He simply states that his fungus grew well 

 on a medium containmg no combmed nitrogen, which from our 

 own experience seems doubtful. ^Moreover, pure cultures were 

 not available to Jodin. Details as to length of time and amoimts 

 of cultures are not given. 



' Jodin, Du role physiologique de I'azote. Compt. Rend. 55: 1S62 (cited by 

 Frank, B., in Lehrbuch der Botanik 1: 376.) 



