CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 167 



By numerous carefully controlled experiments Koch has proved that 

 it is impossible to produce the typical alterations of miliary tubercu- 

 losis by the inoculation of other matters than the bacilli; in these ex- 

 periments he has taken all necessary precautions to avoid confusion 

 with spontaneous tuberculosis, and to exclude all infection from any 

 accidental source of the subjects on which he operated. He concludes 

 that the presence of the bacillus in the tuberculous masses is not a sim- 

 ple concomitant of the tuberculous process, but the cause, and that we 

 must recognize in the bacilli the cause of tuberculosis, hitherto unsus- 

 pected, but now evident in the form of a vegetable parasite. 



Koch has found this parasite in all forms of scrofula and tubercle in 

 man and animals, and in 109 inoculated subjects (rabbits, guinea pigs, 

 and cats) in the nodosities of the lungs. 



Add to this that Villemin and Klebs have demonstrated that the 

 tubercle of man, on inoculation, produces phthisis pulmonalis in ani- 

 mals, and that this inoculated iihthisis is transmissible by inoculation 

 to other animals. 



Johne mentions a case of snccesstul inoculation of tubercle from 

 man to man, and Staug a case of the accidental infection of the sou of 

 healthy parents by habitual drinking of the warm milk of a tubercu- 

 lous cow. 



Another argument in favor of the identity of the disease in man and 

 animals is the perfect analogy of the disease as regards heredity and 

 contagion in the two. 



The heredity in man is shown by the presence of the disease in the 

 fetal offspring of tuberculous parents. Walshe records the frequency 

 of abortion and sterility in tuberculous patients. The doctrine of the 

 contagion of tuberculosis in man has been sustained by Galen, Norton, 

 Swieten, Home, Maret, and many later observers. Instances are 

 quoted of infection through clothes and beds, and from husband to 

 wife. Wichmann, in 1780, said that one death in six in the population 

 of Zurich was from tuberculosis, and details the different channels of 

 direct and indirect contagion, going so far as to advocate a sui)ervision 

 of the sale of old bedding and clothing. CuUen, at the same date? 

 speaks of its ])ropagating itself most readily in the warm climates of 

 Southern Enrojje, where (Italy, Portugal) to the present day the cloth- 

 ing, bedding, and other agents used about a person deceased of phthisis 

 are invariably destroyed. Lydtin con(;ludes : 



1. That tnbercnlnsis has lieon observed in all warm-blooded animals submitted to 

 domestication or deprived of their liberty. 



2. Tnbercnlosis of animals and of man present analogons manifestations in the liv- 

 ing and in the cadaver. 



3. The course and termination of the two maladies are the same in man and animals^ 



4. The tubercular masses, and, above all, the expectoration of phthisical men de- 

 termines tuberculosis in animals when these masses are introduced into the latter by 

 the respiratory or digestive api)aratus, or by a deep wound. Tuberculosis inoculated 

 from man to aninuils can be thenceforward transmitted from one animal to another, 

 producing in all cases tuberculosis. 



