Chemische Physiologie 
301 
fungi can be isolated as pure cultures, without interference from bacterial 
growth, by the use of 20—30% of gelatin in the culture medium. None 
of the forms studied, including at least fourteen species, shows any power 
of assimilating free nitrogen when grown in nitrogen-free media under 
the conditions of the investigations. Myceliopkthora and probably Fusarium 
show no such power even in nitrogen-containing media. Myceliopkthora 
when growing in nitrogen-containing solutions assimilates different portions 
of nitrogen in different concentrations of the nitrogen compound. The 
nitrogen assimilated is approximately 2% of the dry weight of the 
mycelium in all concentrations where the fungus is able to use all the 
nitrogen, in this case up to and including M/250. In higher concentration, 
where the nitrogen is in excess of what the fungus can use, the amount 
of nitrogen assimilated increases up to 5,5% in the case of the M/10 
concentration. Also, the optimum growth as indicated by dry weight 
occurred where the fungus could use all the nitrogen, in which case the 
amount of nitrogen assimilated was 2% of the dry weight. The amount 
of combined nitrogen taken up from the air, by cultures standing exposed, 
does not seem to be sufficient to make appreciable difference in the 
nitrogen content, either in nitrogen-free or in nitrogen-containing media. 
These fungi do not seem to be able to use nitrogen in all its forms, 
since analysis failed to show that they could use that present in the 
dextrose of the culture medium. The Kjeldahl method of analysis is 
capable of a degree of accuracy which will reduce the limit of error very 
near to 0,1 mg. for each determination in analyses involving very small 
quantities of nitrogen. In analyses involving larger quantities of nitrogen, 
the error may be reduced to 0,3 of 1 %. A very perceptible growth of 
mycelium is possible in practically nitrogen-free media, but in such cases 
the nitrogen content is found by analysis to fall within the limit of error 
of the method. Furthermore, the mycelium shows a starved, shriveled 
condition, as if deficient in some necessary element. In these cases, 
mycelia having a dry weight of 3—6 mg. gave amounts of nitrogen 
within the limits of error. Conversely, this may be something of a 
qualitative index of nitrogen-fixation, for, when the dry weight of mycelium 
is not more than 6—8 mg., there is little or no probability of nitrogen- 
fixation. J. Ramsbottom (London;. 
KUNKEL, 0., The influence of starch, peptone, and sugars on 
the toxity of various nitrates to Mo7iilia sitophila (Mont.) 
Sacc. (Bull. Torr. Bot. Club 1913, 40, 625—639). 
The author’s summary is as follows: 1. The degree of toxity of 
barium nitrate, aluminium nitrate, ferric nitrate, and urea 
nitrate to Monilia sitophila depends on the organic substance contained 
in the media in which these salts are offered. 
2. Barium nitrate is more toxic in peptone media than in starch 
media, while aluminium nitrate and ferric nitrate are more toxic 
in starch media than in peptone media. 
3. Barium nitrate has practically the same toxicity in starch media 
that it has in either glucose or fructose media. Its toxicity in peptone 
media is the same as its toxicity in galactose media. 
4. The toxicity of aluminium nitrate in galactose media is the 
same as its toxicitiy in starch media. Its toxicity in fructose is much 
greater than in peptone on glucose. 
