Dastur.— The Mode of Infection by Smut in Sugar-cane . 397 
buds, unless wounded. £ Thick ’ varieties have been infected only through 
wounded eyes. So far as is known, the infection can take place only through 
unthickened scale hairs. The bud can produce a spore-bearing shoot within 
two months after infection. It is also evident that the hyphae from the 
infected bud, even when it remains dormant, travel into the main stem, 
thence to the tillers and secondary shoots, which ultimately may produce 
spore-bearing shoots. If from such a plant setts are used as { seeds ’ before 
it produces spore-bearing shoots, which are the only visible sign of the 
presence of the disease, the new plants are bound to give infected stools, 
and setts containing inoculated buds which were dormant when planted 
have given smutted stools. These facts explain why setts taken from stools, 
which show no external sign of infection and look healthy in the absence of 
the spore-bearing shoots, give a new crop of smutted plants. It is there- 
fore essential that setts used for inoculation experiments should be micro- 
scopically examined before they are inoculated. 
Summary. 
It is shown that infection of the sugar-cane smut takes place only 
through the buds. The sporidia on germinating penetrate the young, thin- 
walled scale hairs. Infection through the cut ends of the setts does not 
take place. 
A bud can produce a spore-bearing shoot within two months after 
infection. Diseased setts when planted give diseased shoots. 
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