20 BULLETIN 1210, U. S. DEPARTMENT OF AGRICULTURE. || 
of exact and comprehensive experiments which are of high scientifie 
value in that he takes into consideration the temperature factor in 
tests of varietal resistance. Ohio wheat, previously almost immune, 
in his experiments yielded as high as 61.9 per cent of bunted heads. 
TABLE 3.—Comparative resistance to bunt shown by well-known varieties of wheat in 
Pye’s experiments. 
Percentage 
bs Percentage Me 
Variety. of bunt. * | Varlety- of bunt. 
PIPRTIGTITIDIIOR.. <n are aoe a ee ne Se 58. 00 | MIG AR Ss oe oy de eau Aa tciclet pond eee 6. 00 
Mederawoms. oir... Moose epee eee | 49100: || Codar eet oS: LU 14. 00 
BSODSecs- tse ect cic. ek saeebphiccecne - ‘«s| 43.00 | IOLANGPE 6. op a shut «nahh gos eee 3.03 
MOGCAUT 2465 bs js obscene ven sade 0 IEEE): 2 RR arrears ae a= ok Baoan nS». 2. 01 
| | 
Hecke’s conclusions in part are that resistance is a varietal charac- 
ter and is transmissible to the progeny in crosses, but that it is 
modified by other factors, one of which is temperature, and that 
varieties react differently to external factors, temperature in par- 
ticular. He is very skeptical as to resistance being constantly re- 
lated to the chara acters of prompt cermination and ‘growth, though 
he recognizes the fact that the s shorter the time from the beginning 
of germination to the appearance of the first leaf, all other factors 
being equal, the less the liability to infection. 
Darnell- Smith (97) finds no evidence that rapidity of growth is 
related to resistance, but notes that Florence, Cedar, and. Medeah, 
all resistant, have but little brush as compared with susceptible 
varieties and suggests that this lack of capacity to hold a larger 
amount of spores may be a factor. Cobb’s (84) observations on 
the amount and character of the brush of the variety Medeah con- 
firm those of Darnell-Smith. 
SUMMARY. 
Bunt of wheat has been known from very early times and is re- 
ferred to by Theophrastus and other early Greek and Roman writers. 
Down to the time of Tillet (1755) bunt was believed to be caused 
by environmental or providential influences. 
In 1755 Tillet proved by experiment its infective character. 
r Prévost (1807) demonstrated the fungous origin and nature of 
unt. 
Kiihn (1858) established the fact that bunt arises from infection of 
the wheat seedling. 
The use of copper sulphate as a bunt preventive was first suggested 
by Schulthess in 1761, and Kiihn (1866) first evolved a formula for 
its use. 
The hot-water treatment of seed grain for the prevention of smuts 
was recommended by Jensen in 1888. 
The use of formaldehy de as a general seed disinfectant was sug- 
gested by Geuther in 1895. 
Maddox (1896) demonstrated that loose smut ( Ustilago tritici) is 
caused by a fungous infection of the blossom, thus establishing the 
fundamental difference between bunt and loose smut. 
Appel (1913) recorded the observation that a bunty crop was caused 
by spores blown from a threshing machine. 
