326 TUBERCULOSIS 



and the Inoculation of the same from Man to Rabbits," in December, 

 1865. From his successful experiments he drew the conclusions 

 that tuberculosis is a specific disease, that it has its origin in an 

 inoculable virus, which can be transferred successfully from man to 

 the rabbit, and that it is. a virulent disease, which should be classified 

 with smallpox, scarlet fever, syphilis, and which can be likened to 

 glanders. Villemin's inoculation experiments with tubercular material 

 were successfully repeated by some; others apparently produced 

 tubercular lesions with morbid, but not tubercular, material and with 

 pieces of glass, rubber, wood, etc., so that Villemin's views were soon 

 discredited. The work of Schueller, Tappeiner, Langhans, Cohnheim, 

 Salmonsen, Baumgarten, Klebs, Chaveau, Bellinger, Kitt, Gerlach, 

 and others, undertaken after the publication of Villeman's investi- 

 gations and continued until the year 1881, gradually demonstrated 

 more and more clearly the infectious nature of tuberculosis. Klebs, 

 Toussaint, and others made attempts to cultivate the unknown living 

 virus of tuberculosis, and Aufrecht and Baumgarten undoubtedly 

 saw tubercle bacilli which they were unable either to stain or to 

 cultivate. It was Robert Koch, however, who finally succeeded in 

 establishing the etiology of tuberculosis, this most important disease 

 of man and many of the domestic animals. 



The cultural methods devised by himself, the experiments he under- 

 took, his deductions and conclusions drawn from them, and his first 

 formal communication are even today a monument and model of 

 classical experimental research work in medicine. Some of those 

 who have followed in his footsteps and profited by his pioneer work 

 appear to have forgotten the debt owed him and have venomously 

 attacked him for the view he took as to the intertransmissibility of 

 bovine and human tuberculosis. This question is as yet by no means 

 fully settled, but in the light of researches made during the last decade 

 it certainly appears that Koch's standpoint was too radical. 



Distribution in Man. Tuberculosis in human beings occurs almost 

 over the entire world. It is absent only at very high altitudes. 

 It occurs at all ages, but the greatest number of advanced cases 

 are found in the middle years of life. The United States Census 

 of 1890 showed that with a population of 76,000,000 there died 

 in that one year 111,059 persons from tuberculosis of the lungs, 

 or about one-ninth of the deaths from all causes were due to pul- 

 monary tuberculosis. In Germany the mortality was still larger, 

 reaching 118,706 in a population of 56,000,000. These figures 

 include only deaths from the pulmonary form of tuberculosis, and 

 convey an incorrect idea of the prevalence of this disease among the 

 human race, because pulmonary tuberculosis is often very chronic, 

 and exists for a long time before it leads to death, and tubercular 

 infections are by no means always fatal, as is frequently believed 

 among the laity. On the contrary, they often heal spontaneously, 

 and death results from different causes in individuals with healed 



