The experiments described in the succeeding chapters were performed upon animals and human beings. The subjects were young and healthy, for the most part; when old or unhealthy subjects were employed, the condition is noted in connection with the experiment. These experiments are not exhaustive; a great deal more work needs to be done before the possibilities of investigation in any of the lines here indicated are exhausted.
The animals used were anesthetized; they were not permitted to suffer, nor to regain consciousness after mutilation. Since these studies are essentially investigations into certain forms of reflex action, the experiments would be absolutely worthless if the animal were conscious of pain, or even if it were so frightened or uncomfortable as to struggle. Aside from any considerations of cruelty, then, it is very essential that no real discomfort be endured by the animals subjected to experiment. It is found that surgical anesthesia lessens the reflexes somewhat, but in many instances this had to be employed. Since the structures concerned are not changed by the anesthetic, but only the liminal value of the neurons, it is evident that whatever reactions are secured must indicate a structural relation of the nerves and centers concerned. On the other hand, if any reaction does not appear, it may be due either to the absence of such structural relations as render the reaction possible, or it may be due to the abnormal conditions of the experiment, or it may be due to the temporary physiological conditions of the neurons concerned in the reaction. For these reasons, no great significance is to be placed upon negative results, unless the experiment is repeated many times under varying conditions. It is probably that those reflexes which persist under anesthesia are those which are most persistent under other abnormal conditions. Ether, chloroform, cocaine, morphine, and ether-alcohol were used to secure either complete or partial narcosis.
Cats,
dogs, guinea-pigs, frogs, toads and white rats were used in the series,
-- besides the human subjects. Cats, dogs, and white rats were most
frequently used. All the reactions described were repeated many times,
in order that the possibility of the effect secured being due to some individual
peculiarity of the subject might be eliminated. Some of the reactions
were repeated more than twenty times. Unless otherwise stated, each
reaction was demonstrated upon at least five different subjects.
Many reactions which seemed anomalous, or which were not found constant,
are withheld from publication until they can be subjected to further investigation.
The human subjects employed were nearly all students of physiology. They were usually kept in ignorance of the nature of the expected reaction and the psychical factor was eliminated in every manner possible under the conditions of the experiment. The students who watched the reactions were often unaware of the location of the center which was being stimulated, and they simply noted, independently, the character of the changes which were occurring. In this manner, the psychical effect of expectation was largely eliminated. After each experiment, the human subject was not used again for several hours, in order that the after effects of one experiment might not possibly affect the next.
The changes in blood pressure which were produced by the manipulation of the centers were measured, in the human subjects, by a modification of the Riva-Rocci apparatus. This sphygmomanometer was found very exact and delicate. It is recommended for the use of those who wish to criticize our results.
Dudgeon’s sphygmograph was used for the pulse tracings. It was secured upon the wrist and the normal tracing first taken. The clock work was stopped during the manipulations and started immediately after the work was finished. The sphymograph was not removed from the wrist until the completion of the experiment. In this way any variations of positions, pressure, etc., were avoided. If the subject were lying down, he was first permitted to rest until all changes produced by the change of position had ceased to be manifested by the pulse. If he seemed at all weary, he was permitted to rest until no further change in pulse or blood pressure could be detected, before beginning the experiment.
The respiratory curves were taken with Marey’s tambour. An extra tambour pan was placed over the apex beat of the heart, in order that the cardiac and respiratory waves might be represented upon a single curve. The needle of the tambour played upon a smoked paper upon the revolving drum of the kymograph. The speed of the kymograph was carefully regulated. The apparatus was not changed during the experiment. The curves as registered by these instruments were varnished and from these tracings the cuts used in illustrating the work were made. The direct stimulation of the viscera of animals was effected by means of electricity. A Du Bois-Raymond induction coil supplied the electrodes. The current was not measured, but was kept very weak. It was usually not perceptible to the touch, though sometimes it was increased. Pricking and pinching the viscera were found rather unsatisfactory unless the stimulation was applied directly to the interior of the viscus under experiment. The injury to the viscus necessitated by the direct application of the pricking to its interior was evaded by using electricity. The electrical current penetrates the walls of the viscera readily, and was found very satisfactory. The stimulation of the visceral walls by electricity is, of course, a condition never found in life, but the abnormal stimulation of the visceral walls by inflammation or by the presence of abnormal substances within the visceral cavities, or in the blood and lymph, is not unusual. The reactions produced by the electrical stimulation depend upon the existence of certain permeable pathways through the nervous system. The relations of the osteopathic centers must depend upon the existence of these same pathways.
The electrical stimulation of the viscera initiates the reflex contraction of certain somatic muscles. The persons who assisted in the experiments held their fingers along the back of the animal subject, and noted the contractions in the muscles as they occurred. The reflex contractions thus produced were recorded, and this information was held suggestive of the location of the center for the viscera being investigated. The stimulation of the centers thus located was found to affect the viscera in connection with them. The electrical stimulation of these centers was found of very little effect unless the electrodes were placed upon the deeper muscles or upon the joint surfaces. Stimulation of the joint surfaces initiated more urgent reflex visceral changes than did stimulation of any other structures. Stimulation of the skin over the centers was slightly effective in some instances. Inasmuch as the skin is normally subject to great variations of temperature and to irritation from any conditions, especially in the savage state, it is evident that no great visceral disturbance can be caused by stimulation of the skin, unless stimuli really injurious or very unusual should be employed.
Stimulating manipulations given with the fingers were found very effective in nearly all cases. These manipulations consisted of quick, vibrating movements, with the fingers between the transverse processes of the vertebrae. The movements were the more effective the deeper were the tissues stimulated. Vibration of the skin and superficial tissues was not very effective; stimulation of the deeper layers of muscles produced greater effects, while such movements as affected the articular surfaces were most effective of all. This stimulation affected the viscera in relation with the center in various manners, which are described in connection with the individual centers.
Deep, steady pressure upon the same tissues caused an effect to be produced upon the viscera which was nearly always the reverse of that following stimulation in the same area. The pressure, or “inhibition” produced the greater effects the more the joint surfaces were affected. The effects of the “bony lesion” were secured by holding the vertebrae in positions of strain. This was usually done by placing the fingers of one hand on opposite sides of the vertebral spines and exerting as much pressure as possible. It is needless to say that this procedure requires both strength and skill on the part of the operator. In the accounts of the experiments given in the following chapters this manipulation is called, for the sake of brevity, the “artificial lesion.” The effects of the artificial lesion are usually the same as the effects of inhibition in the same area, but under abnormal circumstances there are some differences in the nature of the effects produced by these manipulations.
The ends sought in planning these experiments were as follows: We hoped to demonstrate, in an undeniable manner, the structural and functional relations underlying the principles of osteopathic therapeutics and diagnosis. We hoped to locate the osteopathic centers more exactly by eliminating the complexity of abnormalities which are almost invariably present in clinic cases. We hoped to locate other centers whose recognition might aid in making osteopathic diagnosis more exact and osteopathic therapeutics more effective. These ends have not been attained in as great a degree as is possible. The series is to be extended indefinitely. It is hoped that the publication of such results as have been attained will be of some value to students and physicians, both as indicative of the possibilities of experimental research and of careful clinical records, as well as a proof of the truth and the strength of the principles of osteopathic diagnosis and therapeutics. Note A.—Some of the facts noted in the dissection of the many cats and dogs killed in these experiments may be suggestive. Every pug dog killed was diseased The fatter they were the more abnormal were the organs. The fattest dog I ever saw was one of these pugs. There was not a normal viscus in the whole body. Dogs and cats which are sick enough to attract attention were always found diseased badly. In the cases of sick animals, muscular contractions were found as often as tests were made for them. These areas of reflex muscular contraction were hypersensitive, also. After these “animal clinic examinations” as we called them, the animals were anesthetized and killed. The viscera affected were always those determined by the “clinic examinations.” There were not so very many of these experiments, and hence many of the points involved in them are reserved for further investigations into the pathology of osteopathic centers. Every animal condemned to death because of a bad temper, etc., was found diseased. The liver was the usual seat of disease for ill-tempered animals, both cats and dogs, but in several instances the brain was affected. In one case of extreme emaciation in a kitten the ovaries were found very cystic. Another kitten, apparently perfectly healthy, had cystic ovaries. The diseases to which domestic animals are subject resemble those of their masters. The presence of tuberculosis among so many of them is a dangerous condition, especially where they are pets of children. Pets should be very carefully watched, and no considerations of sentiment should be permitted to prevent a painless death for the pet found diseased. Temporary sickness, as from over eating, may not be fatal, but the presence of a mastoid abscess, for example, with its drippings of infected pus, or the wheezing breath of tuberculosis, or any discharge from any of the orifices of the body, should indicate a very hasty and merciful execution. Persistent sore eyes and nasal catarrh should be held capital offenses. |