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Prof. H. Garman, who has given the question much attention, thus explains the fundamental points of the theory:

"Suppose a farmer selects from a litter of pigs two lots of three each as nearly alike as possible, treats them exactly alike as to food and shelter, but with a clean, sharp needle punctures the fore-leg of the members of one lot. A comparison of the two lots at the end of a determined period would probably show little difference between them. This is inoculation, in a coarse way, minus the virus. Now suppose

he introduce on the point of a needle into the fore-legs of one of his lots of hogs some well-known chemical, and at the end of a short period all three of this lot show symptoms of swine plague and finally die of this disease. And suppose that he and his neighbors repeated this experiment again and again, and find that in the majority of cases the hogs inoculated in this way die of swine plague, and that those not so treated are exempt. (1) Would not this amount to a demonstration that the chemical substance used produced hog cholera when introduced into the system by inoculation? Now let him feed this chemical substance to his hogs, or introduce it into their bodies in other ways, and suppose that in most cases death by hog cholera is the result. Suppose, further, that this substance is always to be found in diseased hogs but never in healthy ones. From this evidence (2) would he not be right in claiming that this substance produced the disease when taken into the system? And would he not show practical sense in thereafter carefully excluding it from the quarters in which his hogs were kept? If, now, he found this same chemical in the bodies of the hogs which had taken the disease spontaneously' (?) would he not have reason for asserting that this substance was the cause of hog cholera?"

It is often the case that the spread of any contagious disease through a herd is marked with peculiarities which are very difficult to explain. An animal in the last stages of lung plague may be introduced into a herd, and even though present there but a few hours a number of animals may be infected, but not all; in fact, in practice in the very worst outbreaks of lung plague with which we have to deal we find animals which have apparently exhibited no signs of the disease which an ordinary observer may detect. This, however, cannot be accepted as evidence that the germ theory is incorrect, for we have no proof (1) that the germs were taken into the system of that particular animal; and (2) that it did not have the disease in a mild form not detected by the ordinary observer.

It is not safe to trust to the observations of the uninitiated when contagious diseases are being dealt with. The writer has condemned and killed animals suffering with contagious pleuro-pneumonia (lung plague) which the owner stoutly asserted had nothing the matter with them. In many such cases the post-mortem revealed lungs weighing thirty or forty pounds, and to the initiated giving all the sounds incident to the disease.

It may be claimed that one division of these bacteria, to which those causing lung plague probably belong, cannot be present in the system without creating the disease in its worst form; but there is another class, of which the bacteris causing tuberculosis (tubercular consumption), may be taken as a type, which may be and are often present in the blood and secretions without, for the time being, creating any dangerous symptoms or producing any real disease; thus the bacteria of tuberculosis may, and undoubtedly does exist, and lay ap

parently dormant in the systems of animals in infected herds and for a considerable time show no effects, but as soon as by a heavy cold, the proper conditions exist for its rapid propagation in the lungs, the disease is exhibited in its most virulent form. It has been claimed that ordinary tuberculosis as we find it among animals, may be caused. by exposure and a violation of the laws of ventilation; but the evidence seems to prove that at some time previous to the animal having been brought under these influences the germs were introduced into its system, and having been introduced there remained dormant until the violations of the laws of health produced that condition which caused the rapid propagation of the bacteria belonging to tuberculosis.

Bad ventilation, exposure to cold winds and rain, over-heating, drinking cold water when very warm, do not therefore produce tuberculosis, for they cannot create the germs of the disease, but these germs, being already in the system, are by the peculiar combination of circumstances, given the opportunity for which they have been waiting, and the disease follows. The violation of nature's laws did not cause it; they simply furnished the fuel, the system already containing the lighted match already for its mission of mischief.

Another class of germs, as seem only to be capable of producing their peculiar disease when they obtain access to certain organs, and to produce it to very different degrees according to the distance of the their introduction from the peculiar organ in which the disease is manifested. Thus, innoculation for contagious pleuro-pneumonia produces a slight form of the disease, which does not reach the contagious point in the animal innoculated, but gives the animal immunity from the disease if taken through the lungs, and in the manner in which the contagion is carried naturally; the same matter, if introduced directly into the lungs, would have probably caused the disease in a more virulent form, and possibly have produced death.

It is almost certain that the germs of many diseases may be taken into the digestive organs, if they are perfectly healthy, with impunity; thus, it is very possible that the germs which cause tuberculosis may pass through the digestive organs of a healthy animal and no effect be noticed. It is true that the risk of the germs getting into the circulation through the assimilated food, has to be taken into consideration, but practical acquaintance with this disease shows us that animals pasturing day after day with infected animals who are constantly throwing off the germs of the disease, must take into their systems numbers of these germs, and yet such animals when exposed to any cause producing disturbance in the lungs, will suddenly exhibit the worst symptoms of the disease. Our experience leads us to assert that an apparently healthy cow may be selected from a herd infected with tuberculosis and submitted to the best judges, who, upon examination may be unable to find any signs of the disease; she may then be care fully housed and cared for; guarded against everything which is supposed to introduce a condition favorable to the propagation of the disease germs, and yet when she calves the chances are over ninety in the hundred that she will immediately develop a rapid form of tuberculosis. The strain on the system produces exactly the condition favorable to the propagation of the germs, and the result naturally follows.

Anothe peculiar class of germs are those which produce our Texan, Spleenic, or Spanish fever, so often met with in this State from the

middle of August to the middle of September. Southern cattle which have been exposed to the miasmatic influences which cause the development of the disease germ, are themselves granted immunity from its effects but during their passage through northern latitudes leave behind them in their urine, droppings and exhalations from their bodies, the germs which will produce the disease in any northern animals which may come in contact with anything which can convey these germs left by the southern animals. Thus far there is nothing about the disease which renders it subject to any other than the general rules which govern all diseases, but here a difference is noted; in the native or northern animal these germs multiply so rapidly as to cause death, while in the southern animal they produced no visible effect; from the bodies of the southern cattle these germs carry death to every northern animal who may be so unfortunate as to get them into his system. No doubt our northern animal, while suffering from the disease, throws these germs off from his system, but they have strangely lost all power of infection and of growth and multiplication; the northern animal cannot infect another animal; the germ has lost its vitality by the passage through his system.

In connection with this class of germ disease, we find that innoculation or an attack of the disease grants immunity from another attack for a period of time which seems to vary with the disease; thus an animal purposely innoculated for contagious pleuro-pneumonia may be brought into contact with a badly diseased animal with impunity; that this immunity from the disease exists for a series of years seems to have been proved; the same effect follows an attack of the disease in its natural form; it gives immunity from subsequent attacks. If then, says the doubter, the germ theory is correct why does this state of affairs exist; why, if the germs of any special disease are introduced into the system of the innoculated animal, does the disease not exhibit itself as before? To this those who have given the subject the greatest amount of investigation and thought answer, that these germs only can exist in the system by the absorption of a certain class of food found therein. By innoculation or by an attack of the disease from which the animal has recovered, the supply of this necessary food is exhausted and it requires a series of years for its accumulation. It being assumed that the germs, even if introduced into the system, cannot live or be increased without the necessary material upon which to live.

It has been claimed that in all outbreaks of contagious disease among live stock the weak and puny suffer first, and that the least loss is among the strong and healthy individuals of the herd. The experience of the writer with all contagious diseases of live stock will not bear this theory out. It is true that there is a larger percentage of loss among the weak and puny members of the head but this is not due to the fact that they alone are attacked. All have about the same chances of taking the germs into their system, but the strong and healthy have by far the greater chance of throwing off the disease by the reaction which nature always offers immediately after the attack. A strong and healthy animal will come through all right while a weaker one would have died under an attack only half as severe. In outbreaks of contagious pleuro-pneumonia we invarably find it the rule that young and thrifty animals in good condition suffer most and are oftenest attacked, and that if there are any young animals not milk

ing in the dairy, they will be not only the first attacked but among them we will experience our greatest percentage of loss.

In our outbreaks of verminous bronchitis (Husk or hoose) the loss is usually among the weaker animals in the herd, the larger members often showing very little of the effects of the disease; not because the strongoli (microscopic worms) which caused the trouble did not find access into their lungs and bronchial tubes, but because the animal possessed sufficient strength to throw them off by the spasmodic coughing which ensues; the strong animal having a much greater chance to relieve itself than the weak and delicate one.

If the germ of any disease is once lodged in the system, nature at once asserts her power to overcome the difficulty and with the strong and robust animal the chances are greatly in her favor, while with the weak the reverse is the case.

The acceptance of the germ theory of disease carries with it the enforced belief that all remedies must be directed towards the prevention of the multiplication of the germs which cause that disease and the destruction of those which are already formed. All investigations in veterinary science must therefore be directed to medicines which shall have the general power of destroying certain germs; like quinine in malarial disease, the medicine must be able to meet with and destroy the bacteria special to the disease. It therefore follows that if we meet with a disease which, like contagious pleuro-pneumonia and spleenic fever, which cannot be controlled by any medicine yet tried, we are forced to the conclusion that this special bacteria possesses a vitality which surpasses all others.

We know that it does not require a very low temperature to destroy the germs of Texan or spleenic fever, that of frost being sufficient, but as we cannot make use of this knowledge to attack the disease in the system of the animal, it is of no avail. We also know that the specific germ of hog cholera will fail to propogate itself at a still lower temperature, but for a like reason this knowledge is of no avail as a practical remedy.

Sources of Nitrogen.

At a recent meeting of the Board, Dr. E. L. Sturtevant startled some of its members by the assertion that "there was not a particle of proof to show that plants ever absorbed, directly, a single ounce of nitrogen from the atmosphere." This blow at the theory that plants derived by far the greater part of their nitrogen from atmospheric sources, has caused no little correspondence and questioning on the part of those who are not yet prepared to accept it.

The burden of scientific evidence is certainly upon the side of Dr. Sturtevant, and Professor R. C. Kedzie, of the Michigan Agricultural College, writes as follows:

"I have said that the plant is incapable of directly appropriating free or atmospheric nitrogen, and this is strictly true. If we plant a seed in a soil deprived of all nitrogen by burning the soil, and water it only with distilled water free from ammonia, the plant will make only a small growth, limited by the amount of nitrogen the seed contained; and the plant itself will contain no more nitrogen than did the seed from which it grew. But if certain classes of plants such as the clovers, peas, beans, vetches, turnips, etc., find a sufficient amount of available nitrogen to secure a vigorous start in growth, they will accumulate a large amount of nitrogen from the air, and store this up

for succeeding crops It is possible that these plants are liable to lay hold of free nitrogen in this way in consequence of the ozone they give off during active growth, since it is well known that ozone will bring free nitrogen into chemical combination and form nitric acid in presence of watery vapor.

"While all plants are capable of drawing a certain amount of required nitrogen from the air, they differ greatly in this respect; one class, characterized by broad leaves and abundant foliage, are capable of drawing almost the whole of their nitrogen from the air and leaving a surplus in their remains for the wants of succeeding crops; while another class, which have narrow leaves and small amount of foliage, are incapable of obtaining a sufficient supply of nitrogen from the air for full development. This distinction is forcibly expressed by Villa of France, who divides plants into nitrogen producers and nitrogen consumers. Red clover may be taken as the type of the nitrogen producers and wheat of the nitrogen consumers. The one is broadleaved, has abundance of foliage, and can arrive at a high degree of development without the use of nitrogenous manures; the other is strap-leaved, has little foliage and cannot reach a satisfactory development without a supply of nitrogen beyond what the air can afford; it demands an accumulated supply of nitrogen in the soil. The pressing demand of all cereal crops is an adequate supply of available nitrogen in the soil. This may be furnished by barnyard manure, by nitrates, salts of ammonia, guano, etc., or it may be furnished by growing crops which have a special power of accumulating nitrogen from the air, burying these in whole or in part in the soil and thus storing up in the soil an amount of available nitrogen for the use of future crops. The power of one crop thus to store up materials for growth of future crops is a fact that lies at the foundation of successful agriculture."

At the recent meeting of the Board at Bellefonte, in a paper on "Recent Investigations on the Nitrogen of Soils and Plants," Professor William Frear of the State College, used the following argument and reasoning:

"The chief controversy has centered about the question of the assimilation by plants of atmospheric nitrogen, excluding that present in the form of ammonia and nitrous and nitric acid; concerning the assimilation of which by leaves or not, there has been no dispute. Priestly was early led to the belief that plants do assimilate free atmospheric nitrogen; De Soussure, twenty years later, after most elaborate investigation, arrived at the opposite conclusion. Boussingault, in 1837-8, made experiments which led him to adopt Priestly's conclusion. Ville, in 1849-52, made experiments which pointed in the same direction; but in 1851-5 Boussingault conducted experiments from which he found that plants receiving air containing nitrogen only in a free state did not live, while others, exposed under exactly the same conditions but receiving nitrogen in a combined form, grew vigorously. Finally, Dr. Pugh, the first president of what is now the Pennsylvania State College, associated himself with Sir John Lawes and Dr. Gilbert at Rothamstead, England, for the purpose of submitting the question to experiment under such conditions that all points in dispute might be tested. After most careful and elaborate experiments upon both cereals and leguminous plants, these distinguished scientists announced as the result of their investigations that free nitrogen is not assimilated by plants.

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