Pasteur then began the series of observations and experiments that finally enabled him to in dicate the causes first of fermentation and then of wound diseases, and to identify some of the agents as members of the class of beings known collectively as bacteria. Lister seized these facts and applied them in surgery. His notion was that the infectious wound diseases were due to the deposit upon the raw surface exposed in open injuries 'of the bacteria floating in the air, and he therefore aimed at the sterilization of the air in the neighborhood of wounds during the course of operations, and at the exclusion of air from wounds during healing. The first was attempted by saturating the air in contact with wound surfaces with the vapor of carbolic acid, and from time to time flooding wounds with solutions of the same substance or of corrosive sublimate; the second object was accomplished by covering wounds during repair with dressings impreg nated with the same antiseptics.
The effect was apparent at once in the results of operations, in lowered mortality, and in recov eries with fewer complications. This plan of treatment, properly called antiseptic, was found, however, to possess serious dangers to both sur geon and patient in the risk of poisoning by the powerful germicides necessarily employed, and the idea began to develop that it was more logical to prevent the inoculation of wounds by bacteria from any source than to attempt their destruction after they had gained entrance. Meanwhile the rapid growth of the science of bacteriology had reached a development that led to the identification of the bacteria causing the common wound diseases and had made surgeons familiar with their distribution, the modes of growth within and outside of the body, and the means of destroying them. The adoption of methods of conducting operations and treating wounds whose purpose was absolutely to pre vent the inoculation of denuded surfaces and tissues by bacteria followed naturally, and now has become universal; and the methods have be come so perfect that wound diseases due to bac teria are rare except after accidental injuries, and some of the most serious of them have vir tually ceased to exist. Few men of the present generation of surgeons have seen hospital gan grene, for example, a disease which has been the cause of thousands of deaths.
The possibilities suggested by the relative free dom from (hanger with which operations were carried ont were quickly appreciated by the medical profession, and the cure of disease by operative measures was soon extended to regions in which, previously, operations had been under taken with the greatest misgiving, or not at all. In consequence. to-day the surgeon opens the cranial and spinal cavities, the thorax, the abdo men. and the joints with perfect confidence that no ill will result from the operation itself; and the benefits that have thus been secured in the relief of lesions of the viscera contained in these cavities cannot be adequately estimated. While the attention of the surgeons during the last two or three decades has been in great part directed toward the perfection of operative technique, progress in other lines has also gone on, and during this period the knowledge of the pathol ogy of many surgical affections has been great ly widened, with corresponding refinements in their treatment.
Not the least important factor in the great progress which has been made in surgery and in medicine also is the method by which the sub ject is now taught, and the candidate for the degree of doctor in medicine is now qualified to undertake the management of the eases he may be called upon to treat. Up to twenty years ago
the instruction to medical students consisted very largely of didactic lectures on the various branches of medicine, supplemented by clinics at which various diseases were demonstrated and their treatment indicated or carried out by the professors. The student but rarely came into contact with the patient. With the better ap preciation of the value of laboratory methods of instruction in the natural sciences which were originally adopted by Hunter and revived and insisted upon by Huxley, they began to be util ized in medical schools, and were gradually elab orated until at present in almost every de partment the student gains his information and experience in that way. The result is that didactic lectures have been greatly diminished in numbers. During the first year of instruction the medical student is introduced in this way to normal human anatomy and physiology; in the laboratories' he studies the gross and minute structure of the body and the functions of the tissues of which it is composed. During the second year he is taught by the same means the general process of deviation from the normal that constitutes disease. During the third year • he studies specific instances of deviations from the normal and learns to identify them as par ticular diseases. At this time he is brought into contact with patients suffering with the diseases with which he has more or less familiarized him self in the laboratory and concerning whose causation and pathology he is fully informed, but whose symptoms and treatments he has yet to learn. The laboratory method is still pur sued, but the dispensary and the hospital have now become for the student his laboratory, and it is in them during his fourth year that he spends the major part of his time. Thus up to the point of gaining experience in performing op erations the student is as well instructed as he can well be. This field is well covered by the performance of operations upon the cadaver where practically all of the major and minor operations can be as well practiced as upon the living; and for special purposes operations can be carried out upon the dog.
As time has progressed and the treatment of diseases peculiar particular regions has come more refined, special divisions of surgery have naturally arisen: and this specialization has contributed in no small degree to the rapid ity of the development of surgery. There are now the well-recognized departments of ophthal mology. treating of diseases of the eye; otology, treating of diseases of the ear; rhinology and larydg,olog,y, treating of diseases of the nose, throat, and larynx: gynecology, treating of dis eases of the female; genitourinary surgery, treating of the diseases of the male; dermatol ogy, treating of diseases of the skin; orthopaedic surgery, treating of deformities growing out of diseases of the bones and joints. In the case of all of these specialties the feature that makes them departments of surgery is the fact that the diseases peculiar to each are treated by me chanical means, either by the application of fixed apparatus to be continually worn through long periods or by bloody or non-bloody proced ures whose duration is brief.