[Vor. 3 
414 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
other saprophytie species. Even those who report fixation 
for the last-mentioned fungi base their conclusions, in the 
majority of cases, upon amounts which are only questionably 
beyond the possibility of experimental error. The literature 
has been frequently reviewed, but for purposes of discussion 
in this and in forthcoming papers, it has been found well to 
give this detailed consideration. No account of N-fixation by 
bacteria is included. 
The experiments of Jodin (’62) are now interesting merely 
in an historical way. He observed fungi, in an impure culture, 
to grow upon media, ‘‘trés sensiblement exemptes de com- 
posés azotés organique ou mineraux." Employing the 
methods of gas analysis, he found that in a sealed vessel the 
amount of molecular nitrogen used was from 6 to 7 per cent 
of the oxygen consumed. 
Hallier (’67) simply reported that he had often observed 
yeasts growing in a nitrogen-free medium, but he realized the 
necessity of quantitative data in order definitely to deter- 
mine the fact of nitrogen fixation. From observations on the 
growth of mould fungi in nitrogen-containing and nitrogen- 
free media Nägeli (780) concluded that mould fungi are 
unable to assimilate free nitrogen. 
Frank ('92) states that he grew certain forms of Peni- 
cillium upon nutrient media lacking nitrogen and then tested 
the media for the presence of nitrogen, securing a positive 
indieation. No quantitative work appears to have been done, 
nor are the quantities of medium employed in either case men- 
tioned. Later he (793) reported growing Penicillium clado- 
sporioides! (—Hormodendron cladosporioides) during ten 
months in nitrogen-free media containing sugar. A culture 
on 65 ce. of solution is reported to have given a fixation of 
3.5 mg. nitrogen. Insufficient details are furnished regard- 
ing methods employed and the use of controls. 
Using Aspergillus niger and Alternaria tenuis as the basis 
of a test, supplementary to a more complete study of bacteria, 
Berthelot (793) reported a fixation of 5.8 to 10.0 mg. in the 
1 In the discussion of literature the writers have written mg names of the 
various organisms just as they are given in the original article 
