590 
Journal of Agricultural Research 
Vol.XXIV.No 7 
will not germinate in a liquid which is not exposed to oxygen. On the 
other hand, these experiments also indicate very strongly that with 
reduced oxygen supply germination still may take place. If it were 
true that in a soil of high moisture content some smut spores were in 
contact with oxygen and others were not, the reduction in germination 
would be clearly explained. 
SUMMARY 
(1) In order to determine the effect of temperature upon the germi¬ 
nation of the spores of Ustilago avenae, spores were germinated in Van 
Tieghem cells or hollow-ground slides at a series of temperatures ranging 
from 4° to 35° C. in beef broth +10 Fuller's scale (Ph 6.1). The opti¬ 
mum for germination is arbitrarily defined as that range of temperature 
over which germination with usual sporidial production will take place 
under these conditions in 24 hours. The minimum temperature for germi¬ 
nation was found to be between 4° and 5° C., the optimum from 15° 
to 28°, and the maximum between 31° and 34°. 
(2) Under these conditions, the minimum and optimum for sporidial 
production are the same as for germination, but the maximum is some¬ 
what lower, ranging from 29° to 30° C. 
(3) The relation of moisture to spore germination was studied by 
placing the spores on layers of agar between filter papers in soil con¬ 
taining 30, 60, and 80 per cent, respectively, of its moisture-holding 
capacity. Germination was found to be highest at 30 per cent, to fall 
off slightly at 60 per cent, and very markedly at 80 per cent. 
(4) Ustilago avenae spores failed to germinate in a suspension exposed 
to an oxygen-free atmosphere. 
LITERATURE CITED 
(1) Appbi. and Gassnbr. 
1907. UNTBRSUCHUNGBN fiSBR UBN BRAND, INSBBSONDBRB DEN FLUGBRAND 
DEs GETREiDEs. In Mitt. K. Biol. Anst. Land u. Forstw., Heft 4, 
p. 9-12, fig. 2. 
(2) Bartholomew, Lucille K., and Jones, Edith Seymour. 
1923. RELATION OF CERTAIN SOIL FACTORS TO THE INFECTION OF OATS BY LOOSE 
SMUT. In Joum. Agr. Research, v. 24, p. 569-575, 2 fig. 
(3) Brefeld, Oscar. 
1895. UNTERSUCHUNGEN AUS DEM GESAMMTGEBIETE DER MYKOLOGIE . . . 
XI. Heft: Die Brandpilze II . . . vi, 98 p., $ col. pi. Munster. 
(4) Clinton, G. P. 
1900. THE SMUTS OF ILLINOIS* AGRICULTURAL PLANTS. Ill. Agr. Exp. Sta. 
Bui. 57, 360 p., illus. 
1906. USTILAGXNALES. In North American Flora, v. 7, p. 1-45. 
(6) Duggar, B. M. 
1901. PHYSIOLOGICAL STUDIES WITH REFERENCE TO THE GERMINATION OF CER¬ 
TAIN FUNGOUS SPORES. In Bot. Gaz., v. 31, p. 38-66. Bibliographi¬ 
cal footnotes. 
(7) Eriksson, Jakob. 
1908. OM SOT I KORN OCH I hafrE. In K. Landtbr. Akad. Handl. och 
Tidskr., Arg. 47, p. 280-285, 4 fig. 
(8) Haberlandt, Friedrich. 
1878-79. DER ALLGEMEINE LANDWIRTHSCHAFTLICHE PFLANZENBAU .Nach 
dem Tode des Verfassers herausgegeben von W. 'Hecke. x, 760 p. 
Wien. 
(9) Heald, F. D. . 
1918. MOST EFFECTIVE METHOD OF CONTROLLING SMUT. In PrOC. I2th Ann. 
Conv. Washington State Grain Growers, Shippers and Millers Assoc., 
p. 26-34, I fig. 
