_Thirdly._ A loss of vital resistance may result from drinking impure water. (See _Watering_, p. 15.) Dr. Graff tells us that "another peculiar appearance, which serves to distinguish these infected spots, is the breaking forth of numerous feeble springs, called oozes, furnishing but a trifling supply of water." Such water is generally considered unwholesome, and will, of course, deprive the system of its vital resistance, if partaken of.
_Fourthly._ A loss of vital resistance may result from exposure; for it is well known that cattle which have been regularly housed every night have escaped the attacks of this malady, and that when suffered to remain at large, they were frequently seized with it.
_Lastly._ The indirect causes of milk fever exist in any thing that can for a time prevent the free and full play of any part of the animal functions. The direct causes of death are chemical action, resulting from decomposition, which overcomes the vital principle.
Professor Liebig tells us, that "chemical action is opposed by the vital principle. The results produced depend upon the strength of their respective actions; either an equilibrium of both powers is attained, or the acting body yields to the superior force. If chemical action obtains the ascendency, it acts as a poison."
_Remarks._--Let us suppose that one, or a combination of the preceding causes, has operated so as to produce an abnormal state in the system of a cow. She is then suffered to remain in the unhealthy district during the night: while there, exposed to the emanations from the soil, she requires the whole force of her vital energies to ward off chemical decompositions, and prevent encroachment on the various functions. A contest commences between the vital force and chemical action, and, after a hard conflict in their incessant endeavors to overcome each other, the chemical agency obtains the ascendency, and disease of a putrid type (milk fever) is the result. The disease may not immediately be recognized, for the process of decomposition may be insidious; yet the milk and flesh of such an animal may communicate the disease to man and other animals. It is well known that almost any part of animal bodies in a state of putrefaction, such as milk, cheese, muscle, pus, &c., communicate their own state of decomposition to other bodies. Many eminent medical men have lost their lives while dissecting, simply by putrefactive matter coming in contact with a slight wound or puncture. Dr. Graff made numerous experiments on dogs with the flesh, &c., of animals having died of milk sickness. He says, "My trials with the poisoned flesh were, for the most part, made on dogs, which I confined; and I often watched the effect of the poison when administered at regular intervals. In the space of forty-eight hours from the commencement of the administration of either the butter, cheese, or flesh, I have observed unequivocal appearances of their peculiar action, while the appetite remains unimpaired until the expiration of the fourth or fifth day." From the foregoing remarks, the reader will agree with us, that the disease is of a putrid type, and has a definite character. What is the reason of this definite character? All diseases are under the control of the immutable laws of nature. They preserve their identity in the same manner that races of men preserve theirs. Milk sickness of the malignant type luxuriates in the locations referred to, for the same reasons that yellow fever is peculiar to warm climates, and consumption to cold ones; and that different localities have distinct diseases; for example, ship fever, jail fever, &c.