Page images
PDF
EPUB

mospheric influences, we may be prepared to comprehend how they may suddenly appear over widely distant regions, and commit ravages so appalling.

So little is really known of the relations which these plants bear to each other, the transformations they undergo, or the seeming transmigrations from one form to another, under change of conditions, &c., that a wide field of inquiry is here open to the young and assiduous microscopist. When we state that the fungus, producing fermentation in yeast, (or the true yeast itself,) will grow upon the diseased scalp of a scrofulous patient, take root, and exist for years without check by the medical treatment attempted; that the fungus from the "ringworm," a disease of the skin, has been successfully used to produce fermentation (and that nearly as briskly as healthy yeast) when added to a barley wort ;* and finally, that forms of fungi considered distinct species cannot be dist nguished from each other, or from yeast, but that their differences seem to be entirely dependent upon the kind of plant, or the diseased animal tissue on which the spores may chance to alight, we may well believe that much remains to be learned before the naturalist will be prepared to fix the place in his system of even the common mildew of our vines and grapes. Accordingly, the best informed mycologists have not determined to what undoubted genus our vine mildew belongs. Minds of the first class are, however, zealously engaged at present in the elucidation of the structure, and in determining the laws which govern these minute and mysterious organisms.

To discover the causes of mildew and rot has exercised the ingenuity of many inquirers. Some believe they have certainly found them in deep trenching, abounding humus, and retentive soils and sub-soils; all of which are highly injurious in seasons of great atmospheric humidity, and conducive to the production of the "rot." Others assume that the cause of the rot is also the cause of the mildew, because they appear about the same time; but we believe without good reason. Both these evils no doubt arise from some derangement affecting the normal functions of the vine-some departure from the conditions of heat and moisture, either in the air or in the soil, which are absolutely demanded for its healthy growth and the maturation of the fruit. This must be self-evident, while it should also be equally clear that these conditions of temperatures and humidity, abnormal or excessive, are aggravated or rendered more injurious by the qualities of soil or position-by some esteemed the direct and specific cause of these evils. A cause for the sudden and wide spread advent of the mildew on our grape leaves and fruit must be found as wide in its operation as is the resultant evil consequence; and must, therefore, be climatic, and climatic only. The outline sketch of the meteorological changes which preceded and accompanied this evil, and the freedom from its extreme effects in localities near wide waters, where these excessive changes of temperature and dryness were especially modified, point to the atmosphere and its fluctuating conditions as the controlling cause of the derangement which prepares for the growth of the fungi spores.

Some may still believe we have not found this cause in the cold nights resulting from extreme dryness, and the hot days following immediately thereafter, because the leaves of the vine were not frozen, nor even appeared to be injured in every case. In reply, we may say that the extreme low temperatures, followed by extreme high heats, accompanied by excessive dryness, are all conditions highly favorable to the development of the spores of the mildew, which feed upon disorganized tissues; and that freezing is not necessary to prepare for decay, may be learned from the following passage from our highest authority in physiological botany. A. de Candolle asserts, that "cold does not kill vegetation by a mechanical action proceeding from congelation of the fluids of vegetables, as some naturalists pretend. We recognize rather a physiological action in this change, for the vitality of the tissue is destroyed by a certain degree of cold, followed by

* Journal of Microscopic Science, January 7, 1866.

a certain degree of heat, according to the peculiar nature of the plant. In the same manner as the gangrene which follows the thawing of a frozen part causes the death of an animal tissue, so the change or putrefaction which follows on rapid thawing will be the principal cause of the death of the vegetable tissue. This is illustrated by the immediate death of hot-house plants when exposed to a temperature several degrees above freezing." Herein lies the philosophy of the change in the tissue of the leaves exposed to intense radiation through dry air at night, followed by intense heats at mid-day in the same drying atmosphere. The minute vessels are ruptured or dried up, and disorganized, so that decay is induced, and the ever-present spores of the fungus at once find a nidus in the decaying matter, for the removal of which they were created, take root, penetrate the leaves, or enwrap the berries, feeding upon the former and choking the latter, and destroying the remaining vitality of both by their rapid expansion and fatal folds.

OZONE AND THE VINE-MILDEW.

There are other atmospheric conditions, resultants of extreme dryness, or extreme humidity, or unusual cold, which indirectly affect the vine, and aid the development of fungous growth. It has been suggested that the relative amount of ozone in the air, which may be a peculiar form of oxygen, (or a component of this gas, if it be compound,) may exert an influence in promoting or preventing the appearance of the fungi on our vines and on other plants Though much remains to be learned respecting the development and character of this mysterious agent, we already know the conditions most favorable to its production, as well as those inimical to its appearance, or at least to the active exhibition of its energies. We know that chemical action increases with increase of heat and diminishes with reduction of temperature, and that ozone is less prevalent in the air during frosty weather. Moisture, to a certain amount, is favorable to chemical action, while an excess is detrimental thereto; and though there is less ozone in the air when very dry, there is still less when it is very moist—a certain degree of humidity being favorable to its development and existence. Dr. Small wood, the meteorologist of Montreal, asserts that ozone is never present in dry air, and that the psychrometer will indicate its presence or absence. He adds. that east and south winds are ozonic at Montreal, and that northeast winds from off the land are not ozonic; also that westerly and northerly winds do not bear ozone with them, though sea breezes with moisture are strongly ozonic. These conditions are, however, modified in other latitudes, as we have observed repeatedly that winds from the N., NE., S.E., and S. W., may be strongly ozonic at our station. Dr. Smallwood also has shown that there is a connexion between the amount of ozone in the air and the health of a district. Thus, during the prevalence of cholera the amount of ozone is least, and the humidity was at the same time diminished. Dr. Moffatt has concluded, from the results of a large number of experiments in England, that ozone plays an important part in controlling or preventing epidemics, generally by removing the cause prevailing in the infected air of a district. Finally, C. Kosman has ascertained at Strasburg, France, that the green portions of all plants exhale ozone, the result of the chemical changes going on at the surface, or in the vessels of the leaf.

The origin of infectious diseases prevailing over wide districts has, in some instances, been shown to be due to the presence of minute fungi, or rather to their germs or spores, which are ever ready to take hold and grow in favorable positions and conditions; and we know that our grape-vines are sufferers from causes having many points of analogy with the above. Now, when we consider that the appearance of mildew is invariably preceded by sudden changes in the atmospheric moisture or dryness, heat and cold; that excessively most air as well as excessively dry air are both unfavorable to the presence of ozone, which

[ocr errors]

acts so energetically in the destruction of fungi; that plants, when in health, give out ozone, and thus protect themselves from the devouring enemy ever ready to pounce upon the unprotected organism, we need not wonder that, during our oppressively moist days and unseasonably cold nights, the chemical changes connected with (or themselves the sources of) the vitality of the plant should be subdued or oppressed, the quantity of ozone in the air and on the leaf be diminished, and the torpid condition of the leaf render it an easy prey to the invisible but omnipresent enemy, and universal mildew be the result.

THE CATTLE PLAGUE IN EUROPE.

BY J. R. DODGE, OF THE DEPARTMENT OF AGRiculture.

The years 1865-'6 will be memorable in the annals of British farm stock. Long will farmers of the island kingdom painfully recur to recent scenes of suffering and pecuniary loss, in yard and field, in shed and byre, when medication seemed worthless and recovery impossible. Three millions of pounds sterling, or fifteen millions of dollars, may be a moderate estimate of the diminution of the meat supply and stock of the farm; but the indirect money losses flowing from the visitation in the cost of treatment and care, in diminished profits of pasturage, reduction of the aggregate stock of farm-yard manures, derangement of crop rotations, failures of farmers of moderate resources, increase in prices of meat, and other items of pecuniary damage, are not at present calculable.

The disease has distinctive characterestics, but they are so numerous that a confusion of names for it has arisen in different countries, at different times. Formerly it was known only as a murrain, a general designation for fatal diseases among cattle. In Germany, where its visits have often excited alarm and elicited medical inquiry, it has been known by a variety of hard words, given in accordance with prevalent theories of its nature, one of them signifying an impaction of the third stomach; others having reference to the condition of the liver; others meaning gastric fever, and malignant dysenteric fever. In France it is called Peste, and Le Typhus contagieux des bêtes bovines. Sometimes it is known as the Siberian Cattle Plague, which is liable to be confounded with the Siberian Boil Plague-an enzootic rather than an epizootic disease. Gamgee formerly called it Contagious Typhoid Plague. Typhus Boum Contagiosus is common upon the continent. In Great Britain it is the Cattle Plague. It is in all these localities the same disease, having the same symptoms, and attended with similar fatality.

HISTORY OF THE DISEASE.

It is deemed probable by European veterinary authorities that rarely has a period of fifty years elapsed without a visitation of some deadly cattle disease. Homer's Iliad, Virgil's Georgics, Columella, and several ancient agricultural writers, attest the correctness of such a view. The history of six hundred years past, more familiarly known, is full of references to these murrains, generally following in the wake of large armies, and spreading desolation among farin herds. These outbreaks were not always the present rinderpest. The Black Death, commencing in 1347, attacked men, horses, cattle, deer, bears. wolves, hares,

and other animals. In 1709 all countries between Russia and France were infected. At this time 70,000 head perished in Naples, 100,000 in Silesia, 300,000 in the Netherlands. In upper Italy the plague was frightful in 1744, when 40,000 perished in Piedmont, 18,000 in Milan, thence passing into Germany and destroying 200,000. From 1745 to 1749 the losses of Denmark were estimated at 280,000. It entered Sweden and destroyed 32.584 cattle in the province of Schonen, leaving alive but two per cent. of the horned stock. In 1745 it appeared in England for the fourth time. In 1774 the cattle of some of the French provinces were almost exterminated, and the losses were reported at 150,000 cattle, worth 15,000,000 francs. Just prior to the close of the last century, in three years of war, Italy lost from 3,000,000 to 4.000.000. Faust estimated a loss of 10,000,000 head of cattle in France and Belgium from 1713 to 1796.

It is officially stated that the rinderpest, since 1711, in Germany alone has carried off 25,000,000 cattle, and that the cases of recovery have averaged but one in four. Such is the fatal character of this disease, which has appeared in all seasons, spares neither young nor old, and is little dependent on external circumstances.

THE DISEASE IN GREAT BRITAIN.

Professor Gamgee cites historical mention of five outbreaks in Great Britain of a disease identical with the present plague; the first in the year 810, extending through Europe, manifesting its greatest power in Britain; the second in 1223 to 1225, attacking respectively Hungary, Austria, Italy, Germany, and the British Isles; the third, nearly five hundred years later, in 1714, at which period all Europe was severely scourged; the fourth in 1745, continuing twelve years, in the third of which 80,000 cattle were destroyed by orders in council, and in the twelfth and last the single county of Cheshire lost 30,000; and again, in 1769, when comparatively few cattle were destroyed. The present or sixth outbreak occurred in June, 1865, after three years of fearful ravages in several portions of eastern Europe. In 1862, in the Austrian dominions, 296,000 attacks were reported, and 152,000 deaths. In 1863 it overran Hungary and its dependencies, as well as Gallicia, attacking 14 per cent. of all the cattle in those countries. Dr. Marsch, veterinary professor at the Agricultural College at Altenburg, Hungary, writes of the recent visitation: "Within the last year the scourge of the rinderpest has caused ravages among the cattle to an enormous extent, chiefly in the eastern crown lands." In 1863 the fatality amounted to 65 per cent. of the cases attacked in Hungary, 77 in east Gallicia, 81 in Croatia and Sclavonia, 83 on the military frontier, 88 in Moravia, 92 in lower Austria, and 94 in west Gallicia.

The origin of the disease in England is thus given by the "commissioners appointed to inquire into the origin and nature of the cattle plague: "*

"Twenty three days at least before the first outbreak in London a parcel of Russian bullocks, the first it is asserted that were brought direct from that country to England, were sold in the metropolitan market by the importer, a London cattle salesman. They had been shipped at Revel, and landed at Hull; part of them had been sold and sent to various places in the north of England, and the rest despatched to London. The southern provinces of Russia, if not the birthplace, are the constant home of a disease which, as we shall hereafter show, is identified with the cattle plague; and to this cause the introduction of the plague into England has been often and confidently ascribed."

*The commission consisted of Earl Spencer, Viscount Cranborne, Councillor Robert Lowe, Dr. Lyon Playfair, C. B., Clare Sewell Read, M. P., Henry Bence Jones, M. D., Richard Quain, M. D., Edmund Alexander Parkes, M. D, and Messrs. John Robinson M'Clean, Thomas Wormald, Robert Cee.y, and Charles Spooner.

Some obscurity hangs over the early history of this transaction, but the general belief is strong among intelligent Englishmen that the germ of the disease was imported from Russia in the cargo above mentioned.

In this second report, the commissioners say that the careful observations of medical officials "point distinctly to contagion as the means by which the plague was originated and propagated in London."

In France, to which country the infection spread, practical and efficacious measures were promptly adopted. Early in September last, transit and importation of all cattle was prohibited, and the refuse of all cattle of infested countries was strictly prohibited on all the frontiers; and the same prohibition was applied to countries bordering on those infested. No cattle were allowed to pass any of the frontiers without rigid and competent inspection. Such measures were adopted immediately upon the report of two professors of the veterinary school at Alfort, who were sent to make returns from official examination of the disease in Germany and England. Notwithstanding all this precaution, the disease was introduced in two different localities, almost simultaneously, in a commune in Pas-de-Calais, by an importation of two Durhams from England, and on the Belgian frontier by a cow purchased in Belgium. By prompt and vigorous action of the government, the disease was completely suppressed by the beginning of November, with the total loss of forty-three cattle. In December it again broke out in the Jardin d'Acclimation of Bois-de-Bologne, introduced by two gazelles imported from England. It spread rapidly to yaks, zebus, goats, and fallow-deer; but all infected animals were at once slaughtered, to the number of thirty-five, and all traces of the disease were extirpated.

In Belgium, where precautionary and radical measures, analogous to those which were so efficacious in France, were adopted, the number of losses has not exceeded four or five hundred.

Returns from South Holland show that out of 29,031 cases 7,410 were slaughtered, 8,966 died, and 9,896, or about twenty-four per cent., recovered. In Utrecht the number of recoveries appear to be unusually large, being 926 to 790 deaths, while few have been slaughtered. Here the action of the authorities was resisted by force, and had to be supported by military detachments; and in some cases the troops were beaten off by large bands of peasants, and were obliged to take the cow-sheds by regular siege.

Its spread in England and Scotland were in accelerating ratio from the period of its first appearance, June 27, 1865, at Islington, in a herd in which were two cows just brought from the metropolitan cattle market. The entire herd, numbering ninety-three, fell victims, with several others purchased afterwards. In certain districts in the vicinity of London four-fifths of all the cattle either died or were slaughtered.

Early in July the disease appeared in Norfolk county; soon after in Suffolk and Shropshire; thence it attacked county after county; and before the end of the month invaded Scotland. By the 14th of October it existed in twenty-nine counties in England, two in Wales, and sixteen in Scotland. The number attacked in the first week of October was 1,054; in the second, 1,729; and in the third, 1,873. Up to this date the whole number attacked was 17,073, of which but 848 had recovered, or less than five per cent.; 7,912 having died, 6,866 been killed, with 2,047 still on the sick-list. An analysis of the published returns shows that the percentage of attacks increased during 1865, and until the cattle plague act went into operation. Up to December, of every 100 cattle on farms or in sheds where the disease had established itself, 44 were attacked; to December 30, 51; and to January 27, 54. Of the total number known to

« PreviousContinue »