Some of the malignant epidemics which visited Europe after seasons of rain and scarcity during the middle ages have been referred with more or less of probability to ergot-disease.[2758] The chronicles of the 6th and 8th centuries note the occurrence of maladies which may be suspected as due to ergotized grain. There is less of doubt regarding the epidemics that prevailed from the 10th century and were frequent in France, and in the 12th in Spain. In the year 1596 Hessen (Hessia) and the adjoining regions were ravaged by a frightful pestilence, which the Medical Faculty of Marburg attributed to the presence of ergot in the cereals consumed by the population. The same disease appeared in France in 1630, in Voigtland (Saxony) in the years 1648, 1649, and 1675; again in various parts of France, as Aquitaine and Sologne, in 1650, 1670, and 1674. Freiburg and the neighbouring region were visited by the same malady in 1702; other parts of Switzerland in 1715-16; Saxony and Lusatia in 1716; many other districts of Germany in 1717, 1722, 1736, and 1741-2.[2759] The last epidemic in Europe occasioned by ergot appears to be that which, after the rainy season of 1816, visited Lorraine and Burgundy, and proved fatal to many people of the poorer class. Ergot disease is sometimes observed in Abyssinia at the present day,[2760] and a few cases of it have even been lately recorded in Bavaria.[2761]
Formation—The true nature of ergot has long been the source of a great diversity of opinion, not set at rest by the admirable researches of L. R. Tulasne, from whose Mémoire sur l’Ergot des Glumacées,[2762] the following account is for the most part extracted.
The formation of ergot often affects only a few caryopsides in a single ear; sometimes, however, more than twenty. In the former case, the healthy development of the other caryopsides is not prevented, but if too many are attacked, the entire ear decays. The more isolated ergots generally grow larger, and attain their greatest size on rye which springs up here and there among other cereals.
The first symptoms of ergot-formation is the so-called honey-dew of rye, a yellowish mucus, having an intensely sweet taste, and the peculiar disagreeable odour frequently belonging to fungi. Drops of this mucus show themselves here and there on the ears in the neighbourhood of diseased grains, and attract ants and beetles of various kinds, especially the yellowish-red Rhagonycha melanura Fabr., but not bees. On this account the beetle in question has been supposed to be instrumental in the development of ergot, and it may possibly be so, but only by transporting the saccharine mucus from one plant to another.
The honey-dew of rye contains neither oil-drops nor starch. After dilution with water, it produces a rapid and abundant separation of cuprous oxide from an alkaline solution of cupric tartrate. Dried over sulphuric acid, it solidifies into a crystalline mass. After a few days the drops of honey-dew dry up and disappear from the ear. The grain at this period becomes completely disintegrated, and devoid of starch.
The ergotized soft ovaries are covered with, and penetrated by a white, spongy, felted tissue, the mycelium of the young fungus. It is made up of slender, thread-like cells, the hyphæ, the outer layer of which consists of radially-diverging cells, the basidia. The whole mycelium forms by its crevices and folds a number of cavities opening externally; from its outer layer, which is also called the hymenium or spermatophorum, an immense number of agglutinated, elongated granules, the conidia, are separated. These cells, the products of the basidia, are not more than four mkm. in length, and give the floral organs the appearance of being covered with a whitish dust. The honey-dew likewise contains an abundance of conidia, but it is only on dilution that they are precipitated and become easily perceptible; the formation of the honey-dew is intimately connected with that of the conidia themselves. Ergot in this primary or mycelium stage was regarded as an independent fungus by Léveillé (1827), who named it Sphacelia segetum. According to Kühn (1863), it may even be directly by germination of the conidia within the ears of rye.
The mycelium penetrates and envelops the caryopsis, with the exception of the apex, and thereby prevents its further growth, destroying especially the epicarp and the embryo. At the base of the caryopsis, there is formed by tumefaction and gradual transverse separation of the thread-cells of the mycelium, a more compact kernel-like body (the future ergot) violet-black without, white within, which gradually but largely increases in size, and ultimately separates from the mycelium as the loose tissue of the latter dries and shrinks up after the completion of its functions. By this growth, the remains of the caryopsis, still recognizable by their hairs and by the rudiments of the style, as well as by the surviving portions of the mycelium-tissue, become visible above the paleæ on the apex of the mature ergot, now projecting prominently from the ear. Very rarely the ergot is crowned by a fully developed seed; in the commercial drug, the apex is usually broken off.
It is evident that in the process of development just described, the very tissue of the caryopsis of the rye does not undergo a transformation, but that it is simply destroyed. Neither in external form, nor in anatomical structure does ergot exhibit any resemblance to a caryopsis or a seed, although its development takes place between the flowering time and that at which the rye begins to ripen. It has been regarded as a complete fungus, and as such was named by De Candolle (1816) Sclerotium Clavus and by Fries Spermædia Clavus.
No further change in the ergot occurs while it remains in the ear; but laid on damp earth, interesting phenomena take place. At certain points, small orbicular patches of the rind fold themselves back, and gradually throw out little white heads. These increase in size, whilst the outer layers of the neighbouring tissue gradually lose their firmness and become soft and rather granular, at the same time that the cells, of which they are made up, become empty and extended. In the interior of the ergot, the cells retain their oil drops unaltered. The heads assume a greyish-yellow colour, changing to purple, and finally after some weeks stretch themselves towards the light on slender shining stalks of a pale violet colour. The stalks often attain an inch in length, with a thickness of about ½ a line. They consist of thin, parallel, closely-felted cell-threads, devoid of fat oil. Ergot is susceptible of this further development only so long as it is fresh, that is to say, at most until the next flowering time of rye. Within this period however, even fragments are capable of development. There are sometimes also produced colourless threads of mould which belong to other fungi, as Verticillium cylindrosporum Corda, and which frequently overgrow the Claviceps.[2763]
At the point where the stalk joins the spherical or somewhat flattened head, the latter is depressed and surrounds the stalk with an annular border. After a short time there appear on the surface of the head, which is ⅒ of an inch in diameter, a number of brownish warts, in which are the openings of minute cavities, the conceptacula or perithecia. On transverse section, they appear arranged radially round the circumference of the head. In each cavity are a large number of delicate sacs, only 3-5 mkm. thick, and about 100 mkm. long, the thecæ or asci, each containing, as is usual in fungi, 8 spores. These are simple thread-shaped cells, filled with a homogeneous solid mass.