476 
Journal of Agricultural Research voi. xxm, No. 6 
heads. Hybrid 128 and Jones Winter Fife belong to this class. Although 
they produce 20 per cent of sound heads, this seems to be due to accident, 
for in crosses with other varieties the descendants do not show evidence 
of having inherited any cumulative resistance whatever from these 
varieties. 
Fortyfold, Red Russian, and Marquis each have differing dilute resist¬ 
ances which reduce the amount of bunt by 10 to 25 per cent. „ When 
added together, as in descendants of crosses between them, the cumula¬ 
tive effect makes a more concentrated resistance, having a value of from 
30 to 60 per cent. In addition to the dilute resistance, Marquis has a 
strong winter-sensitive resistance with a value of 50 to 60 per cent in 
spring-sown grain which is ineffective in preventing bunt when the seed 
is fall sown. That is, if Marquis is sown in the fall, only the dilute 
resistance is operative, for it produces but 10 to 20 per cent less bunt than 
the most susceptible varieties; if sown in the spring, the strong winter- 
sensitive factor becomes functional, and the resulting crop produces 60 
to 75 per cent less bunt than the completely susceptible varieties. There 
is some evidence that all the different resistances are somewhat winter- 
sensitive, for the facultative wheats (those that may be sown either in 
the fall or in the spring, being true spring wheats but fairly winter hardy) 
are known to produce more bunt from fall seedings. Florence also regis¬ 
ters a higher degree of bunted heads in the fall-sown tests. 
Turkey, Florence, and Alaska each have differing concentrated 
resistances which reduce the amount of bunt 70 to 75 per cent, compared 
with the standard susceptible varieties. These concentrated resistances 
are also cumulative in effect when brought together by crossing, the 
resulting descendants segregating into immune, very resistant, various 
stages of dilute resistant, and completely susceptible classes. 
LITERATURE CITED 
(1) Arthur, J. C. 
1889. smut op wheat and oats. Ind. Agr. Exp. Sta. Bui. 28, 23 p., 7 fig. 
(2) Bippen, R. H. 
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Sei., v. 2, pt. 2, p. 109-128. 
(3) - 
1912. STUDIES IN THE INHERITANCE OP DISEASE RESISTANCE. II. In Jour. 
Agr. Sci., v. 4, pt. 4, p. 421-429. 
(4) BiolETTi, Frederic T. 
1901. the phylloxera op the vine. Calif. Agr. Exp. Sta. Bui. 131, 16 p. f 
2 fig. 
(5) Blaringhem, L. 
1914. VALEUR SP^CIPIQUE DES DIVERS GROUPMENTS DE BL^S (TRITICUM). 
Inst. Pasteur, M6m. Lab. Biol. Agr. 1, 99 p., 12 fig., 2 pi. 
(6) Blumenthal, Ferdinand. 
1898. UEBER DIE VERANDERUNG DES TETANUSGIPTES IM THIERK 6 RPER UND 
seine beziehung zum antitoxin. In Deut. Med. Wchnschr., Jahrg. 
24, No. 12, p. 185-188. 
(7) Brown, William. 
1917. STUDIES IN THE PHYSIOLOGY OP PARASITISM. I. THE ACTION OP BOTRY- 
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p. 348. 
( 8 ) CarlETON, Mark Alfred. 
1899. CEREAL RUSTS OP THE UNITED STATES: A PHYSIOLOGICAL INVESTIGATION. 
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(9) Cobb, N. A. 
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