Zur Biologie Geranium- bewohnender Uredineen 
159 
3. Tranzschel, in „Travaux du Musée Botanique de l’Academie Impé¬ 
riale des Sciences de St. Pétersburg“, livr. II, 1904, p. 15, 1905, p. 13. 
4. Klebahn in Sorauer, Zeitsckr. für Pflanzenkrankh. 1905, p. 70, 1912, p. 327. 
5. —, Pilze in Cryptogamenflora der Mark Brandenburg, Bd. Va, 
H. 3, p. 534. 
6. —, ibid. Bd. Va, H. 2, p. 216. 
7. Tréboux, Annal. Mycol. 1912, Bd. X, p. 305 u. 557. 
8. Bubak, Einige neue oder kritische Uro myces - Arten. Sitzungsber. Kgl. 
Böhm. Gesellschaft der Wissensch. in Prag, IL Classe, 1902. 
9. Bock, Beiträge zur Biologie der Uredineen. Centralbl. f. Bacter. II. Abt. 
1908, Bd. XX, p. 579. 
On some chemical activities of Citromyces: 
Utilization of nitrogenous substances, and effects 
of heavy metals in the medium. 
By 
F. Alex. Me dermott, 
Mellon Institute of Industrial Research, University of Pittsburgh, 
Pittsburgh, Pa., U. S. A. 
As is well known, a number of molds can utilize urea, uric acid, 
hippuric acid, guanine, guanidine, and glycocoll as sources of nitrogen 1 ) 
and it seemed that it might be of interest to try some similar experiments 
with two cultures of Citromyces, which happened to be at hand, so a 
series of tests were accordingly made, and the results are presented here in. 
The cultures were those of Citromyces glaber and Citromyces Pfef- 
ferianus, and had been obtaind about a year previous from the „Central¬ 
stelle für Pilzculturen“. The standard medium contained %: agar 1,5, 
cane-sugar 1,0, NH 4 N0 3 0,5%, MgS0 4 (cryst.) 0,2, K 2 HP0 4 0,2. In 
the tests the ammonium nitrate was replaced by the nitrogen-containing 
substance in a proportion sufficient to introduce approximately the same 
amount of nitrogen. 
In the case of uric acid, only a small portion of the acid intro¬ 
duced actually went into solution. Both species, however, grew rapidly 
under these conditions, showing ready utilization of this substance as a 
source of nitrogen. 
Hippuric acid was utilized much less readily by both species. 
C. Pfefjerianus started rather more readily on it than did C. glaber, but 
both grew very slowly, the growth being compact, and with the hypliae 
spreading but little beyond the edges of dense growth. Thinking that 
the acidity of this substance might cause this checking of the growth 
another set was tried, in which the acidity was neutralized with potassium 
carbonate before sterilization; upon this medium, both species started to 
grow promptly, C. glaber showing the greater early development; neither 
species, however, reached normal growth, the cultures remaining nearly 
white, with only a slight development of the green conidias; after the 
1 ) See W. Benecke in Lafars Handbuch d. Techn. Mycologie 1907, 1 : 
Stickstoffquellen der Eiimyceten , p. 401—408; Czapek, Biochemie 1905, 2, p. 104ff. 
