Brefeld; in other cases three secondary spores may become conjoined, and it is not uncommon to see the conjugating band itself burst and produce a mycelial thread.

Under favourable conditions a few germinating secondary spores will form a dense involved mass of mycelium, bearing a vast number of conidia of the first and second generation; and under the microscope these may be seen in all stages of growth. When the mycelium for any reason ceases to grow, a crop of conidia is at once produced. Sometimes the mycelial threads become furnished with an enormous number of short joints or constrictions, giving the threads a necklace-like appearance. Ultimately this chain or necklace breaks up into separate joints, and each joint acts as a conidium. Each conidium thus formed in a chain is capable of producing other necklacelike growths of conidia.

An elaborate essay on bunt and smut was published in Paris in 1877 under the name of Aperçu Systématique des Ustilaginées, by Alexandre Fischer de Waldheim. This author at one time advocated the idea of bunt and smut fungi living in two forms on different plants in the supposed style of corn mildew on the barberry bush, because he failed to infect corn experimentally, and because he had probably learned that "experience had taught the practical farmer" that (according to Phillipar) the barberry bush, a stinking plant, when in bloom, was in some places the cause of bunt. No experiment is, however, easier than the artificial and direct infection of wheat with bunt and smut.

Wheat becomes affected with bunt by the spores of the fungus being sown with the grain. The spores do not germinate whilst they are dry and stored with the seed, but in and on the damp ground after the grain has been planted. The whole series of changes illustrated in Fig. 116 takes place on and in the ground, and when the attenuated thread at F is produced, it readily finds its way, aided by its inconceivable fineness, into the tissues

of the young wheat plant by entering the first-formed organs of transpiration in the infant plant. The spores themselves do not, of course, enter the stomata, and the germ-tubes probably do not attack the rootlets unless the latter are broken or injured, although it has been said by Le Maout and Decaisne, in their General System of Botany, that the spores can pierce the tissues of the roots. The germ-tube, when once within the infant plant, speedily ascends the stem. It is now by no means difficult to trace the course of the mycelium up the shaft of the affected plant, and an instance has been recorded by the Rev. M. J. Berkeley in vol. ii. of the Journal of the Royal Horticultural Society, 1847, where a streak of bunt appeared upon the outside of the stem of a wheat plant. Mr. Berkeley was the first to publish a description and illustration of germinating bunt spores, with the conjugating spores borne on the germ-thread. This was seven years before the publication of L. R. Tulasne's memoir in the Annales des Sciences Naturelles, Botanique, series iv., vol. i., 1854. Mr. Berkeley, although at first inclined to look upon these conjoined bodies as having something to do with the reproduction of bunt the appearances seen in some Alge indicating this to him—abandoned this first and correct opinion for the idea that the conjugated bodies were parasites of bunt. He described the growth as a Fusisporium, partly owing to the septate spores, under the name of F. inosculans. It is curious that Tulasne illustrated the conjoined spores of germinating bunt as non-septate, and therefore unlike a Fusisporium, and since 1854 this view appears to have been generally accepted as correct; but last year Dr. Oscar Brefeld, in his elaborate work, Botanische Untersuchungen über Hefenpilze, correctly illustrate the germinating secondary spores as furnished with septa, sometimes three and sometimes four, precisely in the style of Fusisporium. This observation, the correctness of which we are able to confirm, proves the accuracy of Mr. Berkeley's observa

tion in 1847. The septa are best seen in the spores which have germinated and borne conidia, and such as have lost their vital material, as at DD, Fig. 116. For spores of Fusisporium illustrated to the same scale as germinating bunt, see Figs. 10, 11, 92, 94, and 96 in this work.

It is easy to prove that bunt in wheat is propagated by the spores of the fungus, for if wheat seeds are dusted with the spores or watered with water containing spores, every wheat plant will come up bunted; whereas neighbouring plants, if not so treated, will come up free from disease.

Bunt spores are said (perhaps on insufficient grounds) to be more or less injurious if mingled with flour and made into bread. We have frequently seen them in flour and bread, together with spores of Urocystis and other fungi. Bunt spores were, we believe, at one time supposed to be the cause of cholera, because they were found in cholera evacuations. Professor Hallier has erroneously referred cholera to the presence of Urocystis occulta, Pre., a fungus common in Britain on rye, as well as to bunt, as may be seen by his Phytopathology, and the reports of Drs. Cunningham and Lewis in the Lancet of 2d, 9th, and 16th January 1869. Fowls have been fed with bunted wheat without any bad result.

A fungus allied to bunt, but still nearer to smut, and named Ustilago grandis, Tul., is said to cause headache and other bad symptoms amongst the men engaged in cutting reeds for thatching, in consequence of their inhaling the abundant spores. The same fungus is said to cause eruptions on the face amongst the labourers of the South of Europe.

When bunt is known to be amongst seed grain it should be washed or steeped in some weak poisonous solution, as the minute spores from bunted grains adhere to the healthy seeds. Water, salt, quicklime slacked with boiling water; sulphate of copper, a quarter of a pound to a bushel of corn, and sulphate of soda have all been recommended.

Sulphate of soda in solution and the seeds afterwards dried with dusted quicklime is said to be one of the best preventive solutions. The lime combines with the soda and forms sulphate of lime or gypsum, whilst caustic alkali is set free. As the spores are lighter than water, mere steeping in brine or even pure water is often effectual, as the spores float, and are easily washed away. It is probable that the presence of a few scattered greasy spores are quite as, if not more, damaging than the whole bunted grains with unbroken seed coats. Some alkaline ley should be added if water is used, as the oil on the surface of the spores combines with the alkali and forms a soapy substance which is fatal to effectual spore germination. Sufficient permanganate of potassium may be added to the water until it becomes rose-coloured, or one per cent of carbolic acid may be mixed with the water. It is not proper for the seed to remain long in these solutions; they should be washed quickly and then allowed to dry. When millers see bunted grains amongst the wheat they generally pass it through a dresser with a strong exhaust, and this draws away the fœtid spores.

Bunt, Tilletia Caries, Tul., seems to be confined in this country to wheat, Triticum vulgare, Vill.; T. sativum, Lam.; and barley, Hordeum distichum, L. Alex. Fischer de Waldheim describes no less than fourteen species of bunt. Some of these, as T. Lolii, Awd., and T. lævis, Kuehn.; the first recorded on three different species of Lolium, and the second on five species of Triticum, including wheat, probably occur in this country. One species attacks five different species of Agrostis, and several other bunt fungi are confined to grasses.

A curious species of bunt named Tilletia bullata, Fl., has recently been found in Scotland on docks, Rumex obtusifolius, L. On the Continent this bunt attacks different species of Polygonum.

CHAPTER XXXI.

SMUT OF CORN.

Ustilago carbo, Tul.

THERE are few fungi more familiar to agriculturists than the common "smut" of corn, so common on wheat, barley, and especially oats. Its black colour, and its profusion of sooty spores produced on impoverished ears of corn, makes it apparent to the least observant. It appears earlier in the season than bunt, with which it is sometimes confounded by rustics. It is in some places called "bunt ear," ," "black ball," "dust brand," and chimney sweeper." Its scientific name is Ustilago carbo, Tul. The generic name is derived from Ustio, a burning, and carbo, charcoal, in reference to the burnt and sooty appearance of the diseased panicle or spike. Farmers look on this fungus with less dread than the fungus of bunt, perhaps because the last is virtually a hidden foe and may cause unexpected sudden and serious loss, whilst smut is always seen, and indeed, makes itself obtrusively apparent. In some districts the loose smutted panicle of oats is ignorantly termed the male plant, the spores of the fungus being esteemed as black pollen, and so more beneficial than harmful. As there is no disgusting odour belonging to the "smut" fungus, it does not spoil the flour to an equal extent with the Tilletia. It is probably not very injurious if taken in food by animals, as fowls are not injured by eating smutted grain. It has, however, been said that the straw of corn that has been infested with the smut fungus is distasteful to cattle in chaff. In bad cases as much as one-third of