four in number-vital, curative, preservative, and symptomatic, or, in other words, to sustain the vitality, to cure the disease, to remove the predisposing cause, and to counteract any urgent symptoms. But in practice he reduces them to two-to suppress, by the use of narcotics, any violent symptoms which tend to exhaust the patient, and to counteract the excessive acidity or alkalinity by the use of contraries. The most common cause of disease, he considers, is "acidity"; therefore, when in doubt, give an alkali.

A system which thus combined the prestige of the humoral pathology with the simplicity of the ancient methodism, and the interest of the new chemistry, was sure to be widely accepted, and traces not only of the theories, but even of the prescriptions of Sylvius survived almost to our own times. The most famous of the latter was the Elixir Proprietatis, which was largely used up to the middle of this century, and which closely resembled the "aromatic sulphuric acid," or elixir of vitriol of our present pharmacopoeia.

But Sylvius has other and better claims to remembrance than that of being founder of a superficial and one-sided medical system. His name is justly immortalised in the human brain, the structure of which he did much to elucidate, and, above all, it is from him that we date the permanent establishment of clinical teaching in public hospitals. Bedside instruction had been given, as we have seen, in classical times, in the ancient Nestorian and Arabic schools, and by mediæval practitioners such as Lanfranc; and the system had been revived for a short period during the renaissance at Padua, when students from every part of Europe flocked to that famous university. But it is to the little infirmary of Leyden, with its twelve beds, that we must look for the true origin of the modern practice of "walking the hospitals". Writing in 1664, Sylvius observes: "I have led my pupils by the hand to medical practice, using a method unknown at Leyden, or perhaps elsewhere, i.e., taking them daily to visit the sick at the public hospital.

THOMAS WILLIS.

313 There I have put the symptoms of disease before their eyes; have let them hear the complaints of the patients, and have asked them their opinions as to the causes and rational treatment of each case, and the reasons for those opinions. Then I have given my own judgment on every point. Together with me they have seen the happy results of treatment when God has granted to our cares a restoration of health; or they have assisted in examining the body when the patient has paid the inevitable tribute to death."

The English representative of the chemical school of medicine was Thomas Willis (1622-75), whose name, like that of Sylvius, is best known from his researches on the structure and blood supply of the brain. But he is superior in many ways to his Flemish contemporary. His observations on the phenomena of disease and the action of drugs are second only (in that age) to those of Sydenham; his speculations on the part played in pathology by the nervous system or "animal spirits" anticipate some of the best results of the Vitalistic school, and his chemical theories, though necessarily imperfect, are less shallow and one-sided than those of Sylvius. According to Willis, the processes which take place in the animal organism are forms of “fermentation,” which he defines as “an internal motion of the particles of any body, tending either to the perfection of the same body or because of its change into another," in short, what we now call "metabolism". Health and disease depend upon the normal or abnormal course of these fermentations, and the physician may be compared to a brewer or vintner, whose business is to watch the process, and to prevent or correct any irregularities. But Willis and his writings hardly received the attention they deserved, for the countrymen of Harvey and Newton were less attracted by chemical theories than by the rival doctrines of the so-called mathematical or mechanical school of which we must now give a brief outline.

NOTES.

Sylvius, Opera Medica, Editio Nova, Trag. ad Rhen., 1695. His letter

on clinical teaching is from Daremberg, Histoire des Sciences Médicales, i. 571; Willis, Remaining medical works of, Englished by S. P., London, 1681. For his biography see the Asclepiad, 1892.

LIV. THE IATRO-MECHANICAL SCHOOL. WHILE the doctrine of the Iatro-chemists, starting from its centre in the Netherlands, blended in the schools of France and Germany with the remains of Galenic and Paracelsic theories, there arose in Italy and England a rival medical system, based upon the more advanced and exact sciences of mechanics and mathematics. This school, variously called the iatro-mathematical, iatro-mechanical, iatro-physical, or physiatric, was a direct product of the new scientific spirit, and its most important precursor was Santoro Sanctorius, professor at Padua, and the friend and colleague of Galileo. Sanctorius passed much of his life seated in a chair-like weighing machine of his own invention, by means of which he discovered the so-called "insensible perspiration,” and found to his amazement that this imperceptible loss exceeds in amount all the other excretions combined. He published the results of countless experiments on himself in his Medicina Statica (1614), a work which, though it naturally attributes an excessive value to the new discovery, was of great use in pointing out the hygienic importance of the skin, in encouraging the introduction of diaphoretic medicines, and above all, in showing that the rules of exact science might be applied to some departments of physiology. He expresses a wish that every one, or at least every physician, could have a similar machine, for not only are changes in weight among the earliest signs of approaching illness, but by taking his meals in such a chair a person would be guarded against irregularity in the quantity of his food, which is one of the most fertile causes of disease.

Sanctorius further invented many ingenious instruments,

SANCTORIUS-BORELLI.

315

in devising some of which he was doubtless assisted by his colleague, the famous professor of mathematics. Thus his thermometers, which he declares will be invaluable in cases of fever, are imitations of the air and water instrument invented by Galileo (1597), slightly altered in shape to adapt them for being held in the mouth or applied to the skin. So, too, his "pulsilogium" is an application of Galileo's principle of the pendulum to measure the rate and regularity of the pulse. But we also find a trocar and cannula, "by which an opening may be rapidly made in the windpipe when suffocation is imminent, especially in infants," and which may also be used for tapping the abdomen in dropsy; a vessel resembling a bronchitis kettle, for distributing steam, narcotic vapours, and cooling odours in the sickroom; and, finally, cupping glasses, fitted with exhausting syringes, described and figured at least twenty years before Guericke is supposed to have invented the air pump. Sanctorius, however, had no idea of establishing a new system of medicine, but rather intended to give more exactness and stability to the old Galenic theories. He belonged, in short, to the pre-Harveian age, and he concealed his most ingenious suggestions in a work where few were likely to look for them, a commentary on the Canon of Avicenna. But his other book, the De Medicinâ Staticâ, had a great effect, and when the discovery of the circulation showed that the most typical of vital processes might be compared to a hydraulic system, even sober-minded physicians began to fancy that the Cartesian doctrine, that the body is a machine and physiology a department of physics, might not be unjustified.

The first attempt to solve the problems of life and disease on these principles was made by Borelli (1608-79), in his famous work, On the Motion of Animals and, as far as the title is concerned, it was a brilliant success. He showed that walking, swimming, flying, etc., are mechanical processes in which muscles and bones play the part of strings and levers, and that the forces used can be estimated mathematically. But when he proceeds to more abstruse

physiological and medical questions, he is less fortunate, and, like Sylvius, bases his whole system upon an error. Borelli declares that muscles, when in action, are increased in bulk, and that their activity is due to a rapid fermentation or explosion caused by the mixture of a drop of nerve fluid with the blood in the muscle. "For Willis has shown that an effervescence occurs when fresh blood is mixed with various liquids." The heart acts in the same way, and expels the blood not so much by contraction as by a swelling up of the walls of the ventricles, just as a bullet is shot from a gun by the expansion of the powder, and the forces employed are not dissimilar, for Borelli calculates that each heart-beat overcomes a resistance equal to 180,000 lb.! He then applies the theory to the explanation of fevers. Such affections are not due, as the "chemists" assert, to an acid, alkaline, saline, or sulphurous state of the humours, for we may drink liquids of those kinds to any amount without causing fever; besides, "I saw at Pisa oil of sulphur injected into a dog's veins, and he was none the worse for it". Nor is abnormal heat the primary symptom, as the Galenists say, for it is itself a result of the increased cardiac activity and more rapid circulation of the blood. This Borelli attributes to some change in the nervous fluid, to explain which he adopts Wharton's theory that the glands are the excretory organs of the nervous system, and so finally concludes that the proximate cause of fever is a blocking up of the minute pores of these glands by some viscid substance. Fevers are to some extent self-limited diseases, for the increased blood flow tends to wash away the viscid matter and thus free the glands; and the alternate accumulation and removal explains the intermittences so common in febrile disorders. The rules of treatment are readily deducible from the theory. The physician should for the most part wait upon Nature, but he may do some good by giving fluid diet to dilute the humours, and by administering drugs such as nitre, which appear to dissolve glutinous substances, or bark, to restore the "tone" of the solids. Bleeding,