KIDNEYS.

In several cases of malarial fever, and in two which had yielded suddenly in the earliest stages, the kidneys presented slate-colored spots, which presented a bronze color upon section to the depth of one-fourth to one-eighth of an inch. Microscopical examination demonstrated that the black granules were not present in these bronzed portions, and that the structures of the kidney were not altered in any recognizable manner. We have in a previous chapter considered the bearing of this fact upon the slate and bronze color of the liver.

CHAPTER VI.

CIRCULATION, RESPIRATION, TEMPERATURE, STATE OF THE SKIN, TONGUE, AND CHANGES OF THE URINE IN INTERMITTENT, REMITTENT, AND CONGESTIVE FEVER.

PRINCIPLES OF TREATMENT BASED UPON THESE OBSERVATIONS.

THE Complete investigation of pathological phenomena demands the accurate determination of the amounts and chemical relations of all the materials entering into the diseased body, and of the transformations through which these materials pass, and of the amounts eliminated, and of the chemical and physical forms and conditions under which they are eliminated; demands the accurate determination of the chemical changes of the constituents of the organs, tissues, apparatus, and blood, and of the forms and conditions under which they are eliminated.

The pathologist has no means of determining the character of the chemical changes going on in the living body during the dif ferent stages of disease.

The pathologist is limited to an examination of the forces developed by these changes, and of those products resulting from these changes, which are eliminated and cast off from the body.

Although it is impossible in the present state of science to deter

mine accurately the amounts of the muscular and nervous forces, and of heat generated during the stages of diseases, still an examination of the mutual relations and disturbances of these forces during the progress of disease, yields invaluable information bearing upon the nature and treatment of diseases. The amount of force generated in the living body, no matter in what peculiar form or mode of force it appears, always stands in direct relation with the amount of matter chemically altered. The great laws of action and reaction, and of the indestructibility of force, apply, as we have before demonstrated, to all the forces which work the animal machinery.

We have instituted, and are still prosecuting, a series of experiments, the object of which is the demonstration that all the forces of animals, physical, chemical, muscular, and nervous, are derived from the chemical changes of the elements entering into their bodies as food, and forming their structures.

The following observations demonstrate, as far as they extend, that the forces of animals are developed by a chemical change of the elements, and are proportional to the amount of chemical change:

These observations, which I have extended to numerous other warm and cold-blooded animals, and to man, together with an examination of the structure and development of the circulatory and respiratory apparatuses of the animal' kingdom, support the fol lowing conclusions:

The intellect, temperature, nervous, and muscular forces, and organic development of animals, are in proportion to the rapidity of the changes of the elements. In warm-blooded animals, which are endowed with intellect of a high order, and possess great nervous and muscular force, and correspondingly developed organs, the changes in their elements are incessant. When starved they lose weight rapidly. In cold-blooded animals, the temperature of which is often below the surrounding medium, and whose nervous system and intellect are feebly developed, the changes in their elements are correspondingly slow. The cur dog lost in six days and fourteen hours one-third of its original weight; whilst the chelonians lived from thirty to sixty days without losing more than from onefourth to one-thirteenth of their original weight. The loss in the former was from six to fifteen times more rapid than in the latter. The loss of weight at the time of death was very nearly equal in warm and cold-blooded animals. The maintenance of the short, vigorous life of the former required as large a supply of organic and inorganic materials as the prolonged existence of the latter. What the warm-blooded animal gained in intensity and power, it lost in duration.

The length of the life of an animal during starvation and thirst, is proportional to the rapidity of the changes of its elements, and, as a necessary consequence, stands in direct relation to its temperature, intellect, and organic development. Warm-blooded animals wasted more rapidly, lived more energetically, and died in a correspondingly shorter time than cold-blooded animals. Amongst cold-blooded animals the chelonians, which were most active in their movements, and whose nervous system was most excited, lived during a time corresponding with their increased nervous and muscular exertions. The female terrapins, whose ovaries and oviducts were filled with hard and soft eggs, lost from 725 to 3313 of

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1 For numerous experiments on this subject, see the author's investigations, published by the Smithsonian Institution—" Investigations, Chemical and Physiological, Relative to Certain American Vertebrata," by Joseph Jones, M.D.; Smithsonian Contributions to Knowledge, 1856.

their weight hourly, and died in the course of twenty-five or thirtyfive days; while the females which had deposited their eggs, and the males, which were free from these anxieties, wasted only onehalf as much per hour-366 to 7 of their whole weight-and lived twice the length of time-from fifty to seventy days.

As the acts of life are carried on in the same general manner in all animals, and as each species and individual has its own peculiar, intellectual, and physical endowments, it follows, as a necessary consequence, that each species and individual, whether belonging to the animal kingdom or to the human race, must have its own amount of chemical change, which develops the forces. The forces developed by these chemical changes are dependent upon the amount of matter chemically altered, and the position and manner in which it is altered. Here is a wide and important field for investigation, as yet almost entirely untrodden.

These facts, although imperfect, are sufficient to demonstrate the necessity in every pathological investigation, of determining the amount of matter chemically altered and thrown off, and the characters of the matters thus eliminated. This can only be accomplished by the determination of the amounts and characters of the matters thrown off from the lungs, skin, kidneys and bowels. We know that it is almost impossible, with the present instruments and methods of investigation, to determine accurately, the changes in quantity of carbonic acid gas thrown off from the lungs under different circumstances of health, during long periods of time, and the difficulties are greatly increased when we attempt to determine the quantity and characters of the excretions of the skin. Any observations with the present instruments and methods of investigations upon the amounts of matter thrown off from the lungs and skin, for long periods during different diseases, must be unsatisfactory if not absolutely impracticable. Happily the pathologist can examine the urine which reflects as in a mirror, the changes going on in the body, and can determine the relations and changes of the animal temperature, circulation, and respiration.

We hope to demonstrate hereafter, by numerous careful observations, that the determination of the relations of the circulation, respiration, and temperature in diseases, is of the greatest importance in enabling the practitioner of medicine to understand the nature and treatment of diseases, and predict with a great degree of certainty, their course and termination. Thus, whenever, as in congestive fever, there is a want of correspondence between the