SMUT OF CORN. 261 



vast quantities of the transparent conidia were filtered 

 through the sand on to the plate below ; and in this posi- 

 tion, beneath the bottom of the flower-pot and in the plate, 

 they formed colonies of yeast-like conidia, and these conidia 

 germinated by producing threads, as we have illustrated 

 them in Fig. 121, 7 and 8. The spores germinate very 

 readily and produce yeast colonies in diluted beer and 

 diluted expressed juice of horse-dung. 



The disease is doubtlessly propagated by the spores of 

 the fungus being blown over the fields and absorbed by 

 the earth, and by the fungus spores which adhere to the 

 seed at the time of sowing. The black spores germinate 

 in the ground, and there produce the secondary and 

 tertiary series of transparent spores illustrated in Fig. 

 121. These spores or conidia of the second and third 

 order at length protrude extremely fine germinal threads, 

 and these threads find their way into the earliest 

 produced stomata of the infant plant. The spawn or 

 mycelium then travels up the stem towards the panicle 

 and attacks the lowermost spikelets first. We have 

 never noticed the upper part of a panicle diseased whilst 

 the lower part has been sound. It may be commonly 

 noticed that every stem, from two to eight or more, on 

 an invaded plant, will show the disease, whilst adjoining 

 plants remain free. The evidence therefore seems com- 

 plete that the infection comes from the ground and 

 travels upwards. It is obvious, therefore, that smut can 

 only be prevented by dressing the seed, as in the case of 

 bunt, and the directions for one apply to the other. A 

 remedy against smut, much in favour in the north of 

 England, and one which is said to never fail, is the pre- 

 paration of the seed, immediately before sowing, with a 

 sprinkling of stale urine, the seeds being afterwards raked 

 in powdered quicklime till the seed is white. Sometimes 

 the seed is prepared with vitriol or sulphate of copper 

 solution, or " bluestone " dissolved in boiling water. One 

 pound of " bluestone " dissolved in five quarts of water 



