culture. He encouraged the archæological researches of Schliemann, and in 1879 was with him in the Troas, and, nine years later, in Egypt, Nubia, and the Peloponnesus. Like von Baer he devoted a great deal of energy to the study of anthropology, particularly craniology. He followed the genetic method of seeking the explanation of things in their origins. He applied that method to the study of medicine. "For me," he said, "medicine does not begin to-day, and I hold it impossible to be completely at home in it, if one does not interpret it genetically." He was the first to write on the relation of medicine to the fine arts. Perhaps it was his sense of historical perspective that made him contemptuous of the trace of humoral pathology that survived in the teachings of the great Viennese pathologist Rokitansky, and made him at the same time distrustful of the doctrines of Darwin, of Koch and von Behring. REFERENCES Blind, Karl: "Personal Recollections of Virchow," North American Review, 1920, vol. 175, pp. 613-24. Geddes, Patrick: "Protoplasm," Encyclopædia Britannica. Tyson, James. The Cell-Doctrine. 1878. Virchow, Rudolf: Cellular Pathology as Based upon Physiological and Pathological Histology (translated by Frank Chance). Wilson, E. B.: The Cell in Development and Inheritance. 1896. CHAPTER XIV THE INTRODUCTION OF ANESTHETICS THE title of Priestley's work, "Experiments and Observations on Different Kinds of Air" (1774, et seq.), gives some indication of how little was known concerning the chemistry of gases in the latter part of the eighteenth century. The composition of the atmosphere had remained undetermined; marsh gas, carbon dioxide, as well as oxygen, nitrogen, and hydrogen, were kinds of air. The names by which we know them had to wait upon their differentiation, upon their analysis, or upon the analysis of the compounds of which they formed parts, such as water, nitric acid and other acids. A great step forward was made when, on August 1, 1774, Priestley in an apparatus from which air was excluded ignited litharge by means of a burning-glass. He tested the factitious air thus obtained by placing in it a piece of lighted charcoal. In the belief that the supporter of combustion is also the supporter of life he put two mice into the newly isolated gas. He then inhaled some of the gas, and observed an exhilarating effect. "Who can tell," he writes, "but in time this pure air may become a fashionable article in luxury? Hitherto only two mice and myself have had the privilege of breathing it." Before the end of the century the investigations of Priestley, Scheele, and others inspired Dr. Thomas Beddoes to found in one of the suburbs of Bristol the Pneumatic Institution to carry on experiments, and to treat patients by means of the newly discovered factitious airs. This enterprise has been described as a scientific aberration, but Beddoes was fortunate in choosing as an assistant to superintend the experiments Humphry Davy, then (1798) nineteen years old. Davy experimented for months with nitrous oxide, which had been discovered some time previously and which in 1793 was produced by heating ammonium nitrate; that is, the process still in use to-day. The fact that it supports combustion like pure oxygen may have directed special attention to it, but it had been declared poisonous, and had even been described as the "principle of contagion." Davy, however, finally ventured on the crucial experiment of inhaling large quantities of the gas. After being subjected to nitrous oxide in an air-tight chamber for an hour and a quarter he inhaled twenty quarts of the pure gas. "A thrilling," he says, in describing the experience, "extending from the chest to the extremities, was almost immediately produced. I felt a sense of tangible extension highly pleasurable in every limb; my visible impressions were dazzling, and apparently magnified; I heard every sound in the room, and was perfectly aware of my situation. By degrees, as the pleasurable sensations increased, I lost all connection with external things; trains of vivid visible images rapidly passed through my mind, and were connected with words in such a manner, as to produce perceptions perfectly novel. I existed in a world of newly connected and newly modified ideas: I theorized, I imagined that I made discoveries. When I was awakened from this semi-delirious trance by Dr. Kinglake, who took the bag from my mouth, indignation and pride were the first feelings produced by the sight of the persons about me. My emotions were enthusiastic and sublime, and for a minute I walked round the room perfectly regardless of what was said to me. As I recovered my former state of mind, I felt an inclination to communicate the discoveries I had made during the experiment. I endeavored to recall the ideas: they were feeble and indistinct; one collection of terms, however, presented itself; and with the most intense belief and prophetic manner, I exclaimed to Dr. Kinglake, 'Nothing exists but thoughts! The universe is composed of impressions, ideas, pleasures and pains!'" The discovery of the properties of "laughing gas" appealed to the popular imagination, and inhaling nitrous oxide became a regular form of entertainment. Davy, made famous by this and other brilliant discoveries, was appointed assistant lecturer in chemistry at the Royal Institution, London, where his youth, scientific acumen, and wonderful powers of expression soon drew upon him the attention of the fashionable world. In 1800, the year preceding his appointment at London, there appeared his "Researches, Chemical and Philosophical, chiefly concerning Nitrous Oxide," which sets forth the following conclusion: “As nitrous oxide in its extensive operation appears capable of destroying physical pain, it may probably be used with advantage during surgical operations in which no great effusion of blood takes place." Davy's suggestion led to no immediate effects in the practice of surgery. Between the years 1820 and 1828 Hickman, a young surgeon of Shropshire, England, excruciated by the sufferings of those upon whom he was called to operate, carried on a series of experiments on animals in order to discover a method of inducing insensibility to pain by means of inhalations. His early experiments were concerned with the study of asphyxiation, animals being rendered unconscious by enclosing them in glass and preventing the access of air or by exposing them to carbon dioxide prepared from calcium carbonate |